:: PCOMPS_2 semantic presentation begin begin theorem Th1: :: PCOMPS_2:1 for R being Relation for A being set st R well_orders A holds ( R |_2 A well_orders A & A = field (R |_2 A) ) proof let R be Relation; ::_thesis: for A being set st R well_orders A holds ( R |_2 A well_orders A & A = field (R |_2 A) ) let A be set ; ::_thesis: ( R well_orders A implies ( R |_2 A well_orders A & A = field (R |_2 A) ) ) assume A1: R well_orders A ; ::_thesis: ( R |_2 A well_orders A & A = field (R |_2 A) ) then A2: R is_reflexive_in A by WELLORD1:def_5; A3: R |_2 A is_reflexive_in A proof let x be set ; :: according to RELAT_2:def_1 ::_thesis: ( not x in A or [x,x] in R |_2 A ) assume x in A ; ::_thesis: [x,x] in R |_2 A then ( [x,x] in R & [x,x] in [:A,A:] ) by A2, RELAT_2:def_1, ZFMISC_1:87; hence [x,x] in R |_2 A by XBOOLE_0:def_4; ::_thesis: verum end; A4: R |_2 A is_connected_in A proof let x, y be set ; :: according to RELAT_2:def_6 ::_thesis: ( not x in A or not y in A or x = y or [x,y] in R |_2 A or [y,x] in R |_2 A ) assume that A5: ( x in A & y in A ) and A6: x <> y ; ::_thesis: ( [x,y] in R |_2 A or [y,x] in R |_2 A ) A7: R is_connected_in A by A1, WELLORD1:def_5; now__::_thesis:_(_(_[x,y]_in_R_&_[x,y]_in_R_|_2_A_)_or_(_[y,x]_in_R_&_[y,x]_in_R_|_2_A_)_) percases ( [x,y] in R or [y,x] in R ) by A5, A6, A7, RELAT_2:def_6; caseA8: [x,y] in R ; ::_thesis: [x,y] in R |_2 A [x,y] in [:A,A:] by A5, ZFMISC_1:87; hence [x,y] in R |_2 A by A8, XBOOLE_0:def_4; ::_thesis: verum end; caseA9: [y,x] in R ; ::_thesis: [y,x] in R |_2 A [y,x] in [:A,A:] by A5, ZFMISC_1:87; hence [y,x] in R |_2 A by A9, XBOOLE_0:def_4; ::_thesis: verum end; end; end; hence ( [x,y] in R |_2 A or [y,x] in R |_2 A ) ; ::_thesis: verum end; A10: R |_2 A c= R by XBOOLE_1:17; A11: R |_2 A is_antisymmetric_in A proof let x, y be set ; :: according to RELAT_2:def_4 ::_thesis: ( not x in A or not y in A or not [x,y] in R |_2 A or not [y,x] in R |_2 A or x = y ) assume A12: ( x in A & y in A & [x,y] in R |_2 A & [y,x] in R |_2 A ) ; ::_thesis: x = y R is_antisymmetric_in A by A1, WELLORD1:def_5; hence x = y by A10, A12, RELAT_2:def_4; ::_thesis: verum end; A13: R |_2 A is_well_founded_in A proof let Y be set ; :: according to WELLORD1:def_3 ::_thesis: ( not Y c= A or Y = {} or ex b1 being set st ( b1 in Y & (R |_2 A) -Seg b1 misses Y ) ) assume A14: ( Y c= A & Y <> {} ) ; ::_thesis: ex b1 being set st ( b1 in Y & (R |_2 A) -Seg b1 misses Y ) R is_well_founded_in A by A1, WELLORD1:def_5; then consider a being set such that A15: ( a in Y & R -Seg a misses Y ) by A14, WELLORD1:def_3; (R |_2 A) -Seg a c= R -Seg a by WELLORD1:14; hence ex b1 being set st ( b1 in Y & (R |_2 A) -Seg b1 misses Y ) by A15, XBOOLE_1:63; ::_thesis: verum end; A16: A c= field (R |_2 A) proof let x be set ; :: according to TARSKI:def_3 ::_thesis: ( not x in A or x in field (R |_2 A) ) assume x in A ; ::_thesis: x in field (R |_2 A) then ( [x,x] in [:A,A:] & [x,x] in R ) by A2, RELAT_2:def_1, ZFMISC_1:87; then [x,x] in R |_2 A by XBOOLE_0:def_4; hence x in field (R |_2 A) by RELAT_1:15; ::_thesis: verum end; A17: R |_2 A is_transitive_in A proof let x, y, z be set ; :: according to RELAT_2:def_8 ::_thesis: ( not x in A or not y in A or not z in A or not [x,y] in R |_2 A or not [y,z] in R |_2 A or [x,z] in R |_2 A ) assume that A18: x in A and A19: y in A and A20: z in A and A21: ( [x,y] in R |_2 A & [y,z] in R |_2 A ) ; ::_thesis: [x,z] in R |_2 A A22: [x,z] in [:A,A:] by A18, A20, ZFMISC_1:87; R is_transitive_in A by A1, WELLORD1:def_5; then [x,z] in R by A10, A18, A19, A20, A21, RELAT_2:def_8; hence [x,z] in R |_2 A by A22, XBOOLE_0:def_4; ::_thesis: verum end; field (R |_2 A) c= A by WELLORD1:13; hence ( R |_2 A well_orders A & A = field (R |_2 A) ) by A16, A3, A17, A11, A4, A13, WELLORD1:def_5, XBOOLE_0:def_10; ::_thesis: verum end; scheme :: PCOMPS_2:sch 1 MinSet{ F1() -> set , F2() -> Relation, P1[ set ] } : ex X being set st ( X in F1() & P1[X] & ( for Y being set st Y in F1() & P1[Y] holds [X,Y] in F2() ) ) provided A1: F2() well_orders F1() and A2: ex X being set st ( X in F1() & P1[X] ) proof consider Y being set such that A3: for x being set holds ( x in Y iff ( x in F1() & P1[x] ) ) from XBOOLE_0:sch_1(); A4: ex x being set st x in Y proof consider x being set such that A5: ( x in F1() & P1[x] ) by A2; take x ; ::_thesis: x in Y thus x in Y by A3, A5; ::_thesis: verum end; for x being set st x in Y holds x in F1() by A3; then Y c= F1() by TARSKI:def_3; then consider X being set such that A6: X in Y and A7: for Z being set st Z in Y holds [X,Z] in F2() by A1, A4, WELLORD1:5; A8: for M being set st M in F1() & P1[M] holds [X,M] in F2() proof let M be set ; ::_thesis: ( M in F1() & P1[M] implies [X,M] in F2() ) assume ( M in F1() & P1[M] ) ; ::_thesis: [X,M] in F2() then M in Y by A3; hence [X,M] in F2() by A7; ::_thesis: verum end; ( X in F1() & P1[X] ) by A3, A6; hence ex X being set st ( X in F1() & P1[X] & ( for Y being set st Y in F1() & P1[Y] holds [X,Y] in F2() ) ) by A8; ::_thesis: verum end; definition let FX be set ; let R be Relation; let B be Element of FX; func PartUnion (B,R) -> set equals :: PCOMPS_2:def 1 union (R -Seg B); coherence union (R -Seg B) is set ; end; :: deftheorem defines PartUnion PCOMPS_2:def_1_:_ for FX being set for R being Relation for B being Element of FX holds PartUnion (B,R) = union (R -Seg B); definition let FX be set ; let R be Relation; func DisjointFam (FX,R) -> set means :: PCOMPS_2:def 2 for A being set holds ( A in it iff ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ); existence ex b1 being set st for A being set holds ( A in b1 iff ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ) proof defpred S1[ set ] means ex B being Element of FX st ( B in FX & $1 = B \ (PartUnion (B,R)) ); consider X being set such that A1: for x being set holds ( x in X iff ( x in bool (union FX) & S1[x] ) ) from XBOOLE_0:sch_1(); reconsider X = X as set ; take X ; ::_thesis: for A being set holds ( A in X iff ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ) let A be set ; ::_thesis: ( A in X iff ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ) thus ( A in X implies ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ) by A1; ::_thesis: ( ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) implies A in X ) assume A2: ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ; ::_thesis: A in X then A c= union FX by XBOOLE_1:109, ZFMISC_1:74; hence A in X by A1, A2; ::_thesis: verum end; uniqueness for b1, b2 being set st ( for A being set holds ( A in b1 iff ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ) ) & ( for A being set holds ( A in b2 iff ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ) ) holds b1 = b2 proof defpred S1[ set ] means ex B being Element of FX st ( B in FX & $1 = B \ (PartUnion (B,R)) ); thus for X1, X2 being set st ( for x being set holds ( x in X1 iff S1[x] ) ) & ( for x being set holds ( x in X2 iff S1[x] ) ) holds X1 = X2 from XBOOLE_0:sch_3(); ::_thesis: verum end; end; :: deftheorem defines DisjointFam PCOMPS_2:def_2_:_ for FX being set for R being Relation for b3 being set holds ( b3 = DisjointFam (FX,R) iff for A being set holds ( A in b3 iff ex B being Element of FX st ( B in FX & A = B \ (PartUnion (B,R)) ) ) ); definition let X be set ; let n be Element of NAT ; let f be Function of NAT,(bool X); func PartUnionNat (n,f) -> set equals :: PCOMPS_2:def 3 union (f .: ((Seg n) \ {n})); coherence union (f .: ((Seg n) \ {n})) is set ; end; :: deftheorem defines PartUnionNat PCOMPS_2:def_3_:_ for X being set for n being Element of NAT for f being Function of NAT,(bool X) holds PartUnionNat (n,f) = union (f .: ((Seg n) \ {n})); begin theorem Th2: :: PCOMPS_2:2 for PT being non empty TopSpace st PT is regular holds for FX being Subset-Family of PT st FX is Cover of PT & FX is open holds ex HX being Subset-Family of PT st ( HX is open & HX is Cover of PT & ( for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) ) ) proof let PT be non empty TopSpace; ::_thesis: ( PT is regular implies for FX being Subset-Family of PT st FX is Cover of PT & FX is open holds ex HX being Subset-Family of PT st ( HX is open & HX is Cover of PT & ( for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) ) ) ) assume A1: PT is regular ; ::_thesis: for FX being Subset-Family of PT st FX is Cover of PT & FX is open holds ex HX being Subset-Family of PT st ( HX is open & HX is Cover of PT & ( for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) ) ) let FX be Subset-Family of PT; ::_thesis: ( FX is Cover of PT & FX is open implies ex HX being Subset-Family of PT st ( HX is open & HX is Cover of PT & ( for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) ) ) ) assume that A2: FX is Cover of PT and A3: FX is open ; ::_thesis: ex HX being Subset-Family of PT st ( HX is open & HX is Cover of PT & ( for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) ) ) defpred S1[ set ] means ex V1 being Subset of PT st ( V1 = $1 & V1 is open & ex W being Subset of PT st ( W in FX & Cl V1 c= W ) ); consider HX being Subset-Family of PT such that A4: for V being Subset of PT holds ( V in HX iff S1[V] ) from SUBSET_1:sch_3(); take HX ; ::_thesis: ( HX is open & HX is Cover of PT & ( for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) ) ) for V being Subset of PT st V in HX holds V is open proof let V be Subset of PT; ::_thesis: ( V in HX implies V is open ) assume V in HX ; ::_thesis: V is open then ex V1 being Subset of PT st ( V1 = V & V1 is open & ex W being Subset of PT st ( W in FX & Cl V1 c= W ) ) by A4; hence V is open ; ::_thesis: verum end; hence HX is open by TOPS_2:def_1; ::_thesis: ( HX is Cover of PT & ( for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) ) ) the carrier of PT c= union HX proof let x be set ; :: according to TARSKI:def_3 ::_thesis: ( not x in the carrier of PT or x in union HX ) assume x in the carrier of PT ; ::_thesis: x in union HX then reconsider x = x as Point of PT ; consider V being Subset of PT such that A5: x in V and A6: V in FX by A2, PCOMPS_1:3; reconsider V = V as Subset of PT ; now__::_thesis:_x_in_union_HX percases ( V ` <> {} or V ` = {} ) ; supposeA7: V ` <> {} ; ::_thesis: x in union HX V is open by A3, A6, TOPS_2:def_1; then A8: V ` is closed ; x in (V `) ` by A5; then consider X, Y being Subset of PT such that A9: X is open and A10: Y is open and A11: x in X and A12: V ` c= Y and A13: X misses Y by A1, A7, A8, COMPTS_1:def_2; ( X c= Y ` & Y ` is closed ) by A10, A13, SUBSET_1:23; then A14: Cl X c= Y ` by TOPS_1:5; Y ` c= V by A12, SUBSET_1:17; then Cl X c= V by A14, XBOOLE_1:1; then X in HX by A4, A6, A9; hence x in union HX by A11, TARSKI:def_4; ::_thesis: verum end; supposeA15: V ` = {} ; ::_thesis: x in union HX consider X being Subset of PT such that A16: X = [#] PT ; A17: X is open by A16; V = ({} PT) ` by A15 .= [#] PT by PRE_TOPC:6 ; then Cl X = V by A16, TOPS_1:2; then X in HX by A4, A6, A17; hence x in union HX by A16, TARSKI:def_4; ::_thesis: verum end; end; end; hence x in union HX ; ::_thesis: verum end; hence HX is Cover of PT by SETFAM_1:def_11; ::_thesis: for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) let V be Subset of PT; ::_thesis: ( V in HX implies ex W being Subset of PT st ( W in FX & Cl V c= W ) ) assume V in HX ; ::_thesis: ex W being Subset of PT st ( W in FX & Cl V c= W ) then ex V1 being Subset of PT st ( V1 = V & V1 is open & ex W being Subset of PT st ( W in FX & Cl V1 c= W ) ) by A4; hence ex W being Subset of PT st ( W in FX & Cl V c= W ) ; ::_thesis: verum end; theorem :: PCOMPS_2:3 for PT being non empty TopSpace for FX being Subset-Family of PT st PT is T_2 & PT is paracompact & FX is Cover of PT & FX is open holds ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & clf GX is_finer_than FX & GX is locally_finite ) proof let PT be non empty TopSpace; ::_thesis: for FX being Subset-Family of PT st PT is T_2 & PT is paracompact & FX is Cover of PT & FX is open holds ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & clf GX is_finer_than FX & GX is locally_finite ) let FX be Subset-Family of PT; ::_thesis: ( PT is T_2 & PT is paracompact & FX is Cover of PT & FX is open implies ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & clf GX is_finer_than FX & GX is locally_finite ) ) assume that A1: PT is T_2 and A2: PT is paracompact and A3: ( FX is Cover of PT & FX is open ) ; ::_thesis: ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & clf GX is_finer_than FX & GX is locally_finite ) consider HX being Subset-Family of PT such that A4: ( HX is open & HX is Cover of PT ) and A5: for V being Subset of PT st V in HX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) by A1, A2, A3, Th2, PCOMPS_1:24; consider GX being Subset-Family of PT such that A6: ( GX is open & GX is Cover of PT ) and A7: GX is_finer_than HX and A8: GX is locally_finite by A2, A4, PCOMPS_1:def_3; A9: for V being Subset of PT st V in GX holds ex W being Subset of PT st ( W in FX & Cl V c= W ) proof let V be Subset of PT; ::_thesis: ( V in GX implies ex W being Subset of PT st ( W in FX & Cl V c= W ) ) assume V in GX ; ::_thesis: ex W being Subset of PT st ( W in FX & Cl V c= W ) then consider X being set such that A10: X in HX and A11: V c= X by A7, SETFAM_1:def_2; reconsider X = X as Subset of PT by A10; consider W being Subset of PT such that A12: ( W in FX & Cl X c= W ) by A5, A10; take W ; ::_thesis: ( W in FX & Cl V c= W ) Cl V c= Cl X by A11, PRE_TOPC:19; hence ( W in FX & Cl V c= W ) by A12, XBOOLE_1:1; ::_thesis: verum end; clf GX is_finer_than FX proof let X be set ; :: according to SETFAM_1:def_2 ::_thesis: ( not X in clf GX or ex b1 being set st ( b1 in FX & X c= b1 ) ) assume A13: X in clf GX ; ::_thesis: ex b1 being set st ( b1 in FX & X c= b1 ) then reconsider X = X as Subset of PT ; consider V being Subset of PT such that A14: X = Cl V and A15: V in GX by A13, PCOMPS_1:def_2; consider W being Subset of PT such that A16: ( W in FX & Cl V c= W ) by A9, A15; take W ; ::_thesis: ( W in FX & X c= W ) thus ( W in FX & X c= W ) by A14, A16; ::_thesis: verum end; hence ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & clf GX is_finer_than FX & GX is locally_finite ) by A6, A8; ::_thesis: verum end; theorem Th4: :: PCOMPS_2:4 for PT being non empty TopSpace for PM being MetrSpace for f being Function of [: the carrier of PT, the carrier of PT:],REAL st f is_metric_of the carrier of PT & PM = SpaceMetr ( the carrier of PT,f) holds the carrier of PM = the carrier of PT proof let PT be non empty TopSpace; ::_thesis: for PM being MetrSpace for f being Function of [: the carrier of PT, the carrier of PT:],REAL st f is_metric_of the carrier of PT & PM = SpaceMetr ( the carrier of PT,f) holds the carrier of PM = the carrier of PT let PM be MetrSpace; ::_thesis: for f being Function of [: the carrier of PT, the carrier of PT:],REAL st f is_metric_of the carrier of PT & PM = SpaceMetr ( the carrier of PT,f) holds the carrier of PM = the carrier of PT let f be Function of [: the carrier of PT, the carrier of PT:],REAL; ::_thesis: ( f is_metric_of the carrier of PT & PM = SpaceMetr ( the carrier of PT,f) implies the carrier of PM = the carrier of PT ) assume A1: f is_metric_of the carrier of PT ; ::_thesis: ( not PM = SpaceMetr ( the carrier of PT,f) or the carrier of PM = the carrier of PT ) assume PM = SpaceMetr ( the carrier of PT,f) ; ::_thesis: the carrier of PM = the carrier of PT then PM = MetrStruct(# the carrier of PT,f #) by A1, PCOMPS_1:def_7; hence the carrier of PM = the carrier of PT ; ::_thesis: verum end; theorem :: PCOMPS_2:5 for PT being non empty TopSpace for PM being MetrSpace for FX being Subset-Family of PT for f being Function of [: the carrier of PT, the carrier of PT:],REAL st f is_metric_of the carrier of PT & PM = SpaceMetr ( the carrier of PT,f) holds ( FX is Subset-Family of PT iff FX is Subset-Family of PM ) by Th4; definition let PM be non empty set ; let g be Function of NAT,((bool (bool PM)) *); let n be Element of NAT ; :: original: . redefine funcg . n -> FinSequence of bool (bool PM); coherence g . n is FinSequence of bool (bool PM) proof g . n is Element of (bool (bool PM)) * ; hence g . n is FinSequence of bool (bool PM) ; ::_thesis: verum end; end; scheme :: PCOMPS_2:sch 2 XXX1{ F1() -> non empty set , F2() -> Subset-Family of F1(), F3( set , set ) -> Subset of F1(), P1[ set ], P2[ set , set , set , set ] } : ex f being Function of NAT,(bool (bool F1())) st ( f . 0 = F2() & ( for n being Element of NAT holds f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } ) ) proof reconsider A = <*F2()*> as Element of (bool (bool F1())) * by FINSEQ_1:def_11; defpred S1[ Element of NAT , FinSequence of bool (bool F1()), set ] means $3 = $2 ^ <* { (union { F3(c,$1) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= $1 & fq = $2 /. (q + 1) holds P2[c,V,$1,fq] } ) where V is Subset of F1() : P1[V] } *>; A1: for n being Element of NAT for x being Element of (bool (bool F1())) * ex y being Element of (bool (bool F1())) * st S1[n,x,y] proof let n be Element of NAT ; ::_thesis: for x being Element of (bool (bool F1())) * ex y being Element of (bool (bool F1())) * st S1[n,x,y] let x be Element of (bool (bool F1())) * ; ::_thesis: ex y being Element of (bool (bool F1())) * st S1[n,x,y] set T = { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = x /. (q + 1) holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } ; now__::_thesis:_for_X_being_set_st_X_in__{__(union__{__F3(c,n)_where_c_is_Element_of_F1()_:_for_fq_being_Subset-Family_of_F1() for_q_being_Element_of_NAT_st_q_<=_n_&_fq_=_x_/._(q_+_1)_holds_ P2[c,V,n,fq]__}__)_where_V_is_Subset_of_F1()_:_P1[V]__}__holds_ X_in_bool_F1() let X be set ; ::_thesis: ( X in { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = x /. (q + 1) holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } implies X in bool F1() ) assume X in { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = x /. (q + 1) holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } ; ::_thesis: X in bool F1() then consider V being Subset of F1() such that A2: X = union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = x /. (q + 1) holds P2[c,V,n,fq] } and P1[V] ; now__::_thesis:_for_a_being_set_st_a_in_X_holds_ a_in_F1() let a be set ; ::_thesis: ( a in X implies a in F1() ) assume a in X ; ::_thesis: a in F1() then consider P being set such that A3: a in P and A4: P in { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = x /. (q + 1) holds P2[c,V,n,fq] } by A2, TARSKI:def_4; ex c being Element of F1() st ( P = F3(c,n) & ( for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = x /. (q + 1) holds P2[c,V,n,fq] ) ) by A4; hence a in F1() by A3; ::_thesis: verum end; then X c= F1() by TARSKI:def_3; hence X in bool F1() ; ::_thesis: verum end; then reconsider T = { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = x /. (q + 1) holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } as Subset-Family of F1() by TARSKI:def_3; reconsider T1 = <*T*> as FinSequence of bool (bool F1()) ; consider y being FinSequence of bool (bool F1()) such that A5: y = x ^ T1 ; reconsider y = y as Element of (bool (bool F1())) * by FINSEQ_1:def_11; take y ; ::_thesis: S1[n,x,y] thus S1[n,x,y] by A5; ::_thesis: verum end; consider g being Function of NAT,((bool (bool F1())) *) such that A6: g . 0 = A and A7: for n being Element of NAT holds S1[n,g . n,g . (n + 1)] from RECDEF_1:sch_2(A1); defpred S2[ Element of NAT ] means len (g . $1) = $1 + 1; A8: for k being Element of NAT st S2[k] holds S2[k + 1] proof let k be Element of NAT ; ::_thesis: ( S2[k] implies S2[k + 1] ) assume A9: len (g . k) = k + 1 ; ::_thesis: S2[k + 1] len (g . (k + 1)) = len ((g . k) ^ <* { (union { F3(c,k) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= k & fq = (g . k) /. (q + 1) holds P2[c,V,k,fq] } ) where V is Subset of F1() : P1[V] } *>) by A7 .= (len (g . k)) + 1 by FINSEQ_2:16 ; hence S2[k + 1] by A9; ::_thesis: verum end; deffunc H1( Element of NAT ) -> Element of bool (bool F1()) = (g . $1) /. (len (g . $1)); consider f being Function of NAT,(bool (bool F1())) such that A10: for n being Element of NAT holds f . n = H1(n) from FUNCT_2:sch_4(); take f ; ::_thesis: ( f . 0 = F2() & ( for n being Element of NAT holds f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } ) ) len <*F2()*> = 1 by FINSEQ_1:39; hence f . 0 = <*F2()*> /. 1 by A6, A10 .= F2() by FINSEQ_4:16 ; ::_thesis: for n being Element of NAT holds f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } let n be Element of NAT ; ::_thesis: f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } defpred S3[ Element of NAT ] means for q being Element of NAT st q <= $1 holds f . q = (g . $1) /. (q + 1); A11: S2[ 0 ] by A6, FINSEQ_1:39; A12: for n being Element of NAT holds S2[n] from NAT_1:sch_1(A11, A8); then A13: (len (g . n)) + 1 = (n + 1) + 1 ; A14: for k being Element of NAT st S3[k] holds S3[k + 1] proof let k be Element of NAT ; ::_thesis: ( S3[k] implies S3[k + 1] ) assume A15: for q being Element of NAT st q <= k holds f . q = (g . k) /. (q + 1) ; ::_thesis: S3[k + 1] let q be Element of NAT ; ::_thesis: ( q <= k + 1 implies f . q = (g . (k + 1)) /. (q + 1) ) assume A16: q <= k + 1 ; ::_thesis: f . q = (g . (k + 1)) /. (q + 1) now__::_thesis:_f_._q_=_(g_._(k_+_1))_/._(q_+_1) percases ( q = k + 1 or q < k + 1 ) by A16, XXREAL_0:1; supposeA17: q = k + 1 ; ::_thesis: f . q = (g . (k + 1)) /. (q + 1) thus f . q = (g . q) /. (len (g . q)) by A10 .= (g . (k + 1)) /. (q + 1) by A12, A17 ; ::_thesis: verum end; supposeA18: q < k + 1 ; ::_thesis: (g . (k + 1)) /. (q + 1) = f . q A19: q + 1 >= 1 by NAT_1:11; q + 1 <= k + 1 by A18, NAT_1:13; then A20: q + 1 in Seg (k + 1) by A19, FINSEQ_1:1; then q + 1 in Seg (len (g . k)) by A12; then A21: q + 1 in dom (g . k) by FINSEQ_1:def_3; A22: q <= k by A18, NAT_1:13; (k + 1) + 1 >= k + 1 by NAT_1:11; then Seg (k + 1) c= Seg ((k + 1) + 1) by FINSEQ_1:5; then q + 1 in Seg ((k + 1) + 1) by A20; then q + 1 in Seg (len (g . (k + 1))) by A12; then q + 1 in dom (g . (k + 1)) by FINSEQ_1:def_3; hence (g . (k + 1)) /. (q + 1) = (g . (k + 1)) . (q + 1) by PARTFUN1:def_6 .= ((g . k) ^ <* { (union { F3(c,k) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= k & fq = (g . k) /. (q + 1) holds P2[c,V,k,fq] } ) where V is Subset of F1() : P1[V] } *>) . (q + 1) by A7 .= (g . k) . (q + 1) by A21, FINSEQ_1:def_7 .= (g . k) /. (q + 1) by A21, PARTFUN1:def_6 .= f . q by A15, A22 ; ::_thesis: verum end; end; end; hence f . q = (g . (k + 1)) /. (q + 1) ; ::_thesis: verum end; deffunc H2( set ) -> set = union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = (g . n) /. (q + 1) holds P2[c,$1,n,fq] } ; deffunc H3( set ) -> set = union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[c,$1,n,fq] } ; set NF = { H3(V) where V is Subset of F1() : P1[V] } ; len (g . (n + 1)) = (n + 1) + 1 by A12; then A23: dom (g . (n + 1)) = Seg ((n + 1) + 1) by FINSEQ_1:def_3; A24: S3[ 0 ] proof let q be Element of NAT ; ::_thesis: ( q <= 0 implies f . q = (g . 0) /. (q + 1) ) assume q <= 0 ; ::_thesis: f . q = (g . 0) /. (q + 1) then A25: q = 0 ; thus f . q = (g . q) /. (len (g . q)) by A10 .= (g . 0) /. (q + 1) by A6, A25, FINSEQ_1:39 ; ::_thesis: verum end; A26: for n being Element of NAT holds S3[n] from NAT_1:sch_1(A24, A14); A27: for V being Subset of F1() st P1[V] holds H3(V) = H2(V) proof deffunc H4( set ) -> Subset of F1() = F3($1,n); let V be Subset of F1(); ::_thesis: ( P1[V] implies H3(V) = H2(V) ) assume P1[V] ; ::_thesis: H3(V) = H2(V) defpred S4[ set ] means for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[$1,V,n,fq]; defpred S5[ set ] means for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = (g . n) /. (q + 1) holds P2[$1,V,n,fq]; A28: for c being Element of F1() holds ( S4[c] iff S5[c] ) proof let c be Element of F1(); ::_thesis: ( S4[c] iff S5[c] ) thus ( ( for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[c,V,n,fq] ) implies for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = (g . n) /. (q + 1) holds P2[c,V,n,fq] ) ::_thesis: ( S5[c] implies S4[c] ) proof assume A29: for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds P2[c,V,n,fq] ; ::_thesis: for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = (g . n) /. (q + 1) holds P2[c,V,n,fq] let fq be Subset-Family of F1(); ::_thesis: for q being Element of NAT st q <= n & fq = (g . n) /. (q + 1) holds P2[c,V,n,fq] let q be Element of NAT ; ::_thesis: ( q <= n & fq = (g . n) /. (q + 1) implies P2[c,V,n,fq] ) assume that A30: q <= n and A31: fq = (g . n) /. (q + 1) ; ::_thesis: P2[c,V,n,fq] fq = f . q by A26, A30, A31; hence P2[c,V,n,fq] by A29, A30; ::_thesis: verum end; assume A32: for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = (g . n) /. (q + 1) holds P2[c,V,n,fq] ; ::_thesis: S4[c] let fq be Subset-Family of F1(); ::_thesis: for q being Element of NAT st q <= n & fq = f . q holds P2[c,V,n,fq] let q be Element of NAT ; ::_thesis: ( q <= n & fq = f . q implies P2[c,V,n,fq] ) assume that A33: q <= n and A34: fq = f . q ; ::_thesis: P2[c,V,n,fq] f . q = (g . n) /. (q + 1) by A26, A33; hence P2[c,V,n,fq] by A32, A33, A34; ::_thesis: verum end; { H4(c) where c is Element of F1() : S4[c] } = { H4(c) where c is Element of F1() : S5[c] } from FRAENKEL:sch_3(A28); hence H3(V) = H2(V) ; ::_thesis: verum end; A35: { H3(V) where V is Subset of F1() : P1[V] } = { H2(V) where V is Subset of F1() : P1[V] } from FRAENKEL:sch_6(A27); then len (g . (n + 1)) = len ((g . n) ^ <* { H3(V) where V is Subset of F1() : P1[V] } *>) by A7 .= (len (g . n)) + 1 by FINSEQ_2:16 ; hence f . (n + 1) = (g . (n + 1)) /. ((len (g . n)) + 1) by A10 .= (g . (n + 1)) . ((len (g . n)) + 1) by A23, A13, FINSEQ_1:4, PARTFUN1:def_6 .= ((g . n) ^ <* { H3(V) where V is Subset of F1() : P1[V] } *>) . ((len (g . n)) + 1) by A7, A35 .= { H3(V) where V is Subset of F1() : P1[V] } by FINSEQ_1:42 ; ::_thesis: verum end; scheme :: PCOMPS_2:sch 3 XXX{ F1() -> non empty set , F2() -> Subset-Family of F1(), F3( set , set ) -> Subset of F1(), P1[ set ], P2[ set , set , set ] } : ex f being Function of NAT,(bool (bool F1())) st ( f . 0 = F2() & ( for n being Element of NAT holds f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : ( P2[c,V,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) } ) where V is Subset of F1() : P1[V] } ) ) proof defpred S1[ set , set , set , set ] means ( P2[$1,$2,$3] & not $1 in union $4 ); consider f being Function of NAT,(bool (bool F1())) such that A1: f . 0 = F2() and A2: for n being Element of NAT holds f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds S1[c,V,n,fq] } ) where V is Subset of F1() : P1[V] } from PCOMPS_2:sch_2(); take f ; ::_thesis: ( f . 0 = F2() & ( for n being Element of NAT holds f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : ( P2[c,V,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) } ) where V is Subset of F1() : P1[V] } ) ) thus f . 0 = F2() by A1; ::_thesis: for n being Element of NAT holds f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : ( P2[c,V,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) } ) where V is Subset of F1() : P1[V] } let n be Element of NAT ; ::_thesis: f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : ( P2[c,V,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) } ) where V is Subset of F1() : P1[V] } deffunc H1( set ) -> set = union { F3(c,n) where c is Element of F1() : for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds ( P2[c,$1,n] & not c in union fq ) } ; deffunc H2( set ) -> set = union { F3(c,n) where c is Element of F1() : ( P2[c,$1,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) } ; set fxxx1 = { H1(V) where V is Subset of F1() : P1[V] } ; set fxxx = { H2(V) where V is Subset of F1() : P1[V] } ; A3: now__::_thesis:_for_V_being_Subset_of_F1()_st_P1[V]_holds_ H1(V)_=_H2(V) deffunc H3( set ) -> Subset of F1() = F3($1,n); let V be Subset of F1(); ::_thesis: ( P1[V] implies H1(V) = H2(V) ) assume P1[V] ; ::_thesis: H1(V) = H2(V) defpred S2[ set ] means for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds ( P2[$1,V,n] & not $1 in union fq ); defpred S3[ set ] means ( P2[$1,V,n] & not $1 in union { (union (f . q1)) where q1 is Element of NAT : q1 <= n } ); A4: now__::_thesis:_for_c_being_Element_of_F1()_holds_ (_S2[c]_iff_S3[c]_) let c be Element of F1(); ::_thesis: ( S2[c] iff S3[c] ) A5: ( ( for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds not c in union fq ) iff not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) proof thus ( ( for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds not c in union fq ) implies not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) ::_thesis: ( not c in union { (union (f . q)) where q is Element of NAT : q <= n } implies for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds not c in union fq ) proof assume A6: for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds not c in union fq ; ::_thesis: not c in union { (union (f . q)) where q is Element of NAT : q <= n } assume c in union { (union (f . q)) where q is Element of NAT : q <= n } ; ::_thesis: contradiction then consider C being set such that A7: c in C and A8: C in { (union (f . q)) where q is Element of NAT : q <= n } by TARSKI:def_4; ex q being Element of NAT st ( C = union (f . q) & q <= n ) by A8; hence contradiction by A6, A7; ::_thesis: verum end; assume A9: not c in union { (union (f . q)) where q is Element of NAT : q <= n } ; ::_thesis: for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds not c in union fq let fq be Subset-Family of F1(); ::_thesis: for q being Element of NAT st q <= n & fq = f . q holds not c in union fq let q be Element of NAT ; ::_thesis: ( q <= n & fq = f . q implies not c in union fq ) assume ( q <= n & fq = f . q ) ; ::_thesis: not c in union fq then A10: union fq in { (union (f . p)) where p is Element of NAT : p <= n } ; assume c in union fq ; ::_thesis: contradiction hence contradiction by A9, A10, TARSKI:def_4; ::_thesis: verum end; thus ( S2[c] iff S3[c] ) ::_thesis: verum proof hereby ::_thesis: ( S3[c] implies S2[c] ) consider q being Element of NAT such that A11: q <= n ; assume A12: for fq being Subset-Family of F1() for q being Element of NAT st q <= n & fq = f . q holds ( P2[c,V,n] & not c in union fq ) ; ::_thesis: ( P2[c,V,n] & not c in union { (union (f . p)) where p is Element of NAT : p <= n } ) ex fq being Subset-Family of F1() st fq = f . q ; hence P2[c,V,n] by A12, A11; ::_thesis: not c in union { (union (f . p)) where p is Element of NAT : p <= n } thus not c in union { (union (f . p)) where p is Element of NAT : p <= n } by A5, A12; ::_thesis: verum end; assume ( P2[c,V,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) ; ::_thesis: S2[c] hence S2[c] by A5; ::_thesis: verum end; end; { H3(c) where c is Element of F1() : S2[c] } = { H3(c) where c is Element of F1() : S3[c] } from FRAENKEL:sch_3(A4); hence H1(V) = H2(V) ; ::_thesis: verum end; { H1(V) where V is Subset of F1() : P1[V] } = { H2(V) where V is Subset of F1() : P1[V] } from FRAENKEL:sch_6(A3); hence f . (n + 1) = { (union { F3(c,n) where c is Element of F1() : ( P2[c,V,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) } ) where V is Subset of F1() : P1[V] } by A2; ::_thesis: verum end; theorem Th6: :: PCOMPS_2:6 for PT being non empty TopSpace st PT is metrizable holds for FX being Subset-Family of PT st FX is Cover of PT & FX is open holds ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) proof let PT be non empty TopSpace; ::_thesis: ( PT is metrizable implies for FX being Subset-Family of PT st FX is Cover of PT & FX is open holds ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) ) assume PT is metrizable ; ::_thesis: for FX being Subset-Family of PT st FX is Cover of PT & FX is open holds ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) then consider metr being Function of [: the carrier of PT, the carrier of PT:],REAL such that A1: metr is_metric_of the carrier of PT and A2: Family_open_set (SpaceMetr ( the carrier of PT,metr)) = the topology of PT by PCOMPS_1:def_8; let FX be Subset-Family of PT; ::_thesis: ( FX is Cover of PT & FX is open implies ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) ) consider R being Relation such that A3: R well_orders FX by WELLORD2:17; defpred S1[ set ] means $1 in FX; consider Mn being Relation such that A4: Mn = R |_2 FX ; assume that A5: FX is Cover of PT and A6: FX is open ; ::_thesis: ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) consider PM being MetrSpace such that A7: PM = SpaceMetr ( the carrier of PT,metr) ; reconsider PM = PM as non empty MetrSpace by A1, A7, PCOMPS_1:36; deffunc H1( Element of PM, Element of NAT ) -> Element of bool the carrier of PM = Ball ($1,(1 / (2 |^ ($2 + 1)))); set UB = { (union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ) where V is Subset of PM : V in FX } ; { (union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ) where V is Subset of PM : V in FX } is Subset-Family of PM proof reconsider UB = { (union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ) where V is Subset of PM : V in FX } as set ; UB c= bool the carrier of PM proof let x be set ; :: according to TARSKI:def_3 ::_thesis: ( not x in UB or x in bool the carrier of PM ) assume x in UB ; ::_thesis: x in bool the carrier of PM then consider V being Subset of PM such that A8: x = union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } and V in FX ; x c= the carrier of PM proof let y be set ; :: according to TARSKI:def_3 ::_thesis: ( not y in x or y in the carrier of PM ) assume y in x ; ::_thesis: y in the carrier of PM then consider W being set such that A9: y in W and A10: W in { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } by A8, TARSKI:def_4; ex c being Element of PM st ( W = Ball (c,(1 / 2)) & c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) by A10; hence y in the carrier of PM by A9; ::_thesis: verum end; hence x in bool the carrier of PM ; ::_thesis: verum end; hence { (union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ) where V is Subset of PM : V in FX } is Subset-Family of PM ; ::_thesis: verum end; then reconsider UB = { (union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ) where V is Subset of PM : V in FX } as Subset-Family of PM ; defpred S2[ Element of PM, Subset of PM, Element of NAT ] means ( $1 in $2 \ (PartUnion ($2,Mn)) & Ball ($1,(3 / (2 |^ ($3 + 1)))) c= $2 ); consider f being Function of NAT,(bool (bool the carrier of PM)) such that A11: f . 0 = UB and A12: for n being Element of NAT holds f . (n + 1) = { (union { H1(c,n) where c is Element of PM : ( S2[c,V,n] & not c in union { (union (f . q)) where q is Element of NAT : q <= n } ) } ) where V is Subset of PM : S1[V] } from PCOMPS_2:sch_3(); defpred S3[ set ] means ex n being Element of NAT st $1 in f . n; consider GX being Subset-Family of PM such that A13: for X being Subset of PM holds ( X in GX iff S3[X] ) from SUBSET_1:sch_3(); reconsider GX = GX as Subset-Family of PT by A1, A7, Th4; take GX ; ::_thesis: ( GX is open & GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) A14: for X being Subset of PT st X in GX holds X is open proof let X be Subset of PT; ::_thesis: ( X in GX implies X is open ) assume A15: X in GX ; ::_thesis: X is open then reconsider X = X as Subset of PM ; consider n being Element of NAT such that A16: X in f . n by A13, A15; now__::_thesis:_X_in_the_topology_of_PT percases ( n = 0 or n > 0 ) ; supposeA17: n = 0 ; ::_thesis: X in the topology of PT thus X in the topology of PT ::_thesis: verum proof consider V being Subset of PM such that A18: X = union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } and V in FX by A11, A16, A17; set NF = { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ; { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } c= bool the carrier of PM proof let a be set ; :: according to TARSKI:def_3 ::_thesis: ( not a in { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } or a in bool the carrier of PM ) assume a in { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ; ::_thesis: a in bool the carrier of PM then ex c being Element of PM st ( a = Ball (c,(1 / 2)) & c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) ; hence a in bool the carrier of PM ; ::_thesis: verum end; then reconsider NF = { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } as Subset-Family of PM ; NF c= Family_open_set PM proof let a be set ; :: according to TARSKI:def_3 ::_thesis: ( not a in NF or a in Family_open_set PM ) assume a in NF ; ::_thesis: a in Family_open_set PM then ex c being Element of PM st ( a = Ball (c,(1 / 2)) & c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) ; hence a in Family_open_set PM by PCOMPS_1:29; ::_thesis: verum end; hence X in the topology of PT by A2, A7, A18, PCOMPS_1:32; ::_thesis: verum end; end; suppose n > 0 ; ::_thesis: X in the topology of PT then consider k being Nat such that A19: n = k + 1 by NAT_1:6; reconsider k = k as Element of NAT by ORDINAL1:def_12; thus X in the topology of PT ::_thesis: verum proof X in { (union { (Ball (c,(1 / (2 |^ (k + 1))))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . q)) where q is Element of NAT : q <= k } ) } ) where V is Subset of PM : V in FX } by A12, A16, A19; then consider V being Subset of PM such that A20: X = union { (Ball (c,(1 / (2 |^ (k + 1))))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . q)) where q is Element of NAT : q <= k } ) } and V in FX ; reconsider NF = { (Ball (c,(1 / (2 |^ (k + 1))))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . q)) where q is Element of NAT : q <= k } ) } as set ; NF c= bool the carrier of PM proof let a be set ; :: according to TARSKI:def_3 ::_thesis: ( not a in NF or a in bool the carrier of PM ) assume a in NF ; ::_thesis: a in bool the carrier of PM then ex c being Element of PM st ( a = Ball (c,(1 / (2 |^ (k + 1)))) & c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . l)) where l is Element of NAT : l <= k } ) ; hence a in bool the carrier of PM ; ::_thesis: verum end; then reconsider NF = NF as Subset-Family of PM ; NF c= Family_open_set PM proof let a be set ; :: according to TARSKI:def_3 ::_thesis: ( not a in NF or a in Family_open_set PM ) assume a in NF ; ::_thesis: a in Family_open_set PM then ex c being Element of PM st ( a = Ball (c,(1 / (2 |^ (k + 1)))) & c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . l)) where l is Element of NAT : l <= k } ) ; hence a in Family_open_set PM by PCOMPS_1:29; ::_thesis: verum end; hence X in the topology of PT by A2, A7, A20, PCOMPS_1:32; ::_thesis: verum end; end; end; end; hence X is open by PRE_TOPC:def_2; ::_thesis: verum end; hence GX is open by TOPS_2:def_1; ::_thesis: ( GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) A21: Mn well_orders FX by A3, A4, Th1; the carrier of PT c= union GX proof let x be set ; :: according to TARSKI:def_3 ::_thesis: ( not x in the carrier of PT or x in union GX ) defpred S4[ set ] means x in $1; assume A22: x in the carrier of PT ; ::_thesis: x in union GX then reconsider x9 = x as Element of PM by A1, A7, Th4; ex G being Subset of PT st ( x in G & G in FX ) by A5, A22, PCOMPS_1:3; then A23: ex G being set st ( G in FX & S4[G] ) ; consider X being set such that A24: X in FX and A25: S4[X] and A26: for Y being set st Y in FX & S4[Y] holds [X,Y] in Mn from PCOMPS_2:sch_1(A21, A23); reconsider X = X as Subset of PT by A24; X is open by A6, A24, TOPS_2:def_1; then A27: X in Family_open_set PM by A2, A7, PRE_TOPC:def_2; reconsider X = X as Subset of PM by A1, A7, Th4; consider r being Real such that A28: r > 0 and A29: Ball (x9,r) c= X by A25, A27, PCOMPS_1:def_4; defpred S5[ Nat] means 3 / (2 |^ $1) <= r; ex k being Element of NAT st S5[k] by A28, PREPOWER:92; then A30: ex k being Nat st S5[k] ; consider k being Nat such that A31: S5[k] and for l being Nat st S5[l] holds k <= l from NAT_1:sch_5(A30); 2 |^ (k + 1) = (2 |^ k) * 2 by NEWTON:6; then ( 2 |^ k > 0 & 2 |^ (k + 1) >= 2 |^ k ) by PREPOWER:6, XREAL_1:151; then A32: 3 / (2 |^ (k + 1)) <= 3 / (2 |^ k) by XREAL_1:118; assume A33: not x in union GX ; ::_thesis: contradiction A34: for V being set for n being Element of NAT st V in f . n holds not x in V proof let V be set ; ::_thesis: for n being Element of NAT st V in f . n holds not x in V let n be Element of NAT ; ::_thesis: ( V in f . n implies not x in V ) assume V in f . n ; ::_thesis: not x in V then V in GX by A13; hence not x in V by A33, TARSKI:def_4; ::_thesis: verum end; A35: for n being Element of NAT holds not x in union (f . n) proof let n be Element of NAT ; ::_thesis: not x in union (f . n) assume x in union (f . n) ; ::_thesis: contradiction then ex V being set st ( x in V & V in f . n ) by TARSKI:def_4; hence contradiction by A34; ::_thesis: verum end; A36: k in NAT by ORDINAL1:def_12; now__::_thesis:_ex_W_being_set_ex_l_being_Element_of_NAT_st_ (_W_in_f_._l_&_x_in_W_) set W = union { (Ball (y,(1 / (2 |^ (k + 1))))) where y is Element of PM : ( y in X \ (PartUnion (X,Mn)) & Ball (y,(3 / (2 |^ (k + 1)))) c= X & not y in union { (union (f . q)) where q is Element of NAT : q <= k } ) } ; A37: x in union { (Ball (y,(1 / (2 |^ (k + 1))))) where y is Element of PM : ( y in X \ (PartUnion (X,Mn)) & Ball (y,(3 / (2 |^ (k + 1)))) c= X & not y in union { (union (f . q)) where q is Element of NAT : q <= k } ) } proof A38: not x9 in union { (union (f . q)) where q is Element of NAT : q <= k } proof assume x9 in union { (union (f . q)) where q is Element of NAT : q <= k } ; ::_thesis: contradiction then consider D being set such that A39: x9 in D and A40: D in { (union (f . q)) where q is Element of NAT : q <= k } by TARSKI:def_4; ex q being Element of NAT st ( D = union (f . q) & q <= k ) by A40; hence contradiction by A35, A39; ::_thesis: verum end; not x9 in PartUnion (X,Mn) proof reconsider FX = FX as set ; assume x9 in PartUnion (X,Mn) ; ::_thesis: contradiction then consider M being set such that A41: x9 in M and A42: M in Mn -Seg X by TARSKI:def_4; A43: M <> X by A42, WELLORD1:1; A44: Mn is_antisymmetric_in FX by A21, WELLORD1:def_5; A45: [M,X] in Mn by A42, WELLORD1:1; then M in field Mn by RELAT_1:15; then A46: M in FX by A3, A4, Th1; then [X,M] in Mn by A26, A41; hence contradiction by A24, A43, A45, A46, A44, RELAT_2:def_4; ::_thesis: verum end; then A47: x9 in X \ (PartUnion (X,Mn)) by A25, XBOOLE_0:def_5; consider A being Subset of PM such that A48: A = Ball (x9,(1 / (2 |^ (k + 1)))) ; 0 < 2 |^ (k + 1) by PREPOWER:6; then A49: x in A by A48, TBSP_1:11, XREAL_1:139; Ball (x9,(3 / (2 |^ (k + 1)))) c= Ball (x9,r) by A31, A32, PCOMPS_1:1, XXREAL_0:2; then Ball (x9,(3 / (2 |^ (k + 1)))) c= X by A29, XBOOLE_1:1; then A in { (Ball (y,(1 / (2 |^ (k + 1))))) where y is Element of PM : ( y in X \ (PartUnion (X,Mn)) & Ball (y,(3 / (2 |^ (k + 1)))) c= X & not y in union { (union (f . q)) where q is Element of NAT : q <= k } ) } by A48, A47, A38; hence x in union { (Ball (y,(1 / (2 |^ (k + 1))))) where y is Element of PM : ( y in X \ (PartUnion (X,Mn)) & Ball (y,(3 / (2 |^ (k + 1)))) c= X & not y in union { (union (f . q)) where q is Element of NAT : q <= k } ) } by A49, TARSKI:def_4; ::_thesis: verum end; reconsider W = union { (Ball (y,(1 / (2 |^ (k + 1))))) where y is Element of PM : ( y in X \ (PartUnion (X,Mn)) & Ball (y,(3 / (2 |^ (k + 1)))) c= X & not y in union { (union (f . q)) where q is Element of NAT : q <= k } ) } as set ; W in { (union { (Ball (y,(1 / (2 |^ (k + 1))))) where y is Element of PM : ( y in V \ (PartUnion (V,Mn)) & Ball (y,(3 / (2 |^ (k + 1)))) c= V & not y in union { (union (f . q)) where q is Element of NAT : q <= k } ) } ) where V is Subset of PM : V in FX } by A24; then W in f . (k + 1) by A12, A36; hence ex W being set ex l being Element of NAT st ( W in f . l & x in W ) by A37; ::_thesis: verum end; hence contradiction by A34; ::_thesis: verum end; hence A50: GX is Cover of PT by SETFAM_1:def_11; ::_thesis: ( GX is_finer_than FX & GX is locally_finite ) for X being set st X in GX holds ex Y being set st ( Y in FX & X c= Y ) proof let X be set ; ::_thesis: ( X in GX implies ex Y being set st ( Y in FX & X c= Y ) ) assume A51: X in GX ; ::_thesis: ex Y being set st ( Y in FX & X c= Y ) then reconsider X = X as Subset of PM ; consider n being Element of NAT such that A52: X in f . n by A13, A51; now__::_thesis:_ex_Y_being_set_st_ (_Y_in_FX_&_X_c=_Y_) percases ( n = 0 or n > 0 ) ; supposeA53: n = 0 ; ::_thesis: ex Y being set st ( Y in FX & X c= Y ) thus ex Y being set st ( Y in FX & X c= Y ) ::_thesis: verum proof consider V being Subset of PM such that A54: X = union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } and A55: V in FX by A11, A52, A53; set NF = { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ; { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } c= bool the carrier of PM proof let a be set ; :: according to TARSKI:def_3 ::_thesis: ( not a in { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } or a in bool the carrier of PM ) assume a in { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } ; ::_thesis: a in bool the carrier of PM then ex c being Element of PM st ( a = Ball (c,(1 / 2)) & c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) ; hence a in bool the carrier of PM ; ::_thesis: verum end; then reconsider NF = { (Ball (c,(1 / 2))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / 2)) c= V ) } as Subset-Family of PM ; A56: for W being set st W in NF holds W c= V proof let W be set ; ::_thesis: ( W in NF implies W c= V ) assume W in NF ; ::_thesis: W c= V then consider c being Element of PM such that A57: W = Ball (c,(1 / 2)) and c in V \ (PartUnion (V,Mn)) and A58: Ball (c,(3 / 2)) c= V ; Ball (c,(1 / 2)) c= Ball (c,(3 / 2)) by PCOMPS_1:1; hence W c= V by A57, A58, XBOOLE_1:1; ::_thesis: verum end; reconsider V = V as set ; take Y = V; ::_thesis: ( Y in FX & X c= Y ) thus Y in FX by A55; ::_thesis: X c= Y thus X c= Y by A54, A56, ZFMISC_1:76; ::_thesis: verum end; end; suppose n > 0 ; ::_thesis: ex Y being set st ( Y in FX & X c= Y ) then consider k being Nat such that A59: n = k + 1 by NAT_1:6; reconsider k = k as Element of NAT by ORDINAL1:def_12; thus ex Y being set st ( Y in FX & X c= Y ) ::_thesis: verum proof X in { (union { (Ball (c,(1 / (2 |^ (k + 1))))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . q)) where q is Element of NAT : q <= k } ) } ) where V is Subset of PM : V in FX } by A12, A52, A59; then consider V being Subset of PM such that A60: X = union { (Ball (c,(1 / (2 |^ (k + 1))))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . q)) where q is Element of NAT : q <= k } ) } and A61: V in FX ; reconsider NF = { (Ball (c,(1 / (2 |^ (k + 1))))) where c is Element of PM : ( c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . q)) where q is Element of NAT : q <= k } ) } as set ; NF c= bool the carrier of PM proof let a be set ; :: according to TARSKI:def_3 ::_thesis: ( not a in NF or a in bool the carrier of PM ) assume a in NF ; ::_thesis: a in bool the carrier of PM then ex c being Element of PM st ( a = Ball (c,(1 / (2 |^ (k + 1)))) & c in V \ (PartUnion (V,Mn)) & Ball (c,(3 / (2 |^ (k + 1)))) c= V & not c in union { (union (f . q)) where q is Element of NAT : q <= k } ) ; hence a in bool the carrier of PM ; ::_thesis: verum end; then reconsider NF = NF as Subset-Family of PM ; A62: for W being set st W in NF holds W c= V proof let W be set ; ::_thesis: ( W in NF implies W c= V ) assume W in NF ; ::_thesis: W c= V then consider c being Element of PM such that A63: W = Ball (c,(1 / (2 |^ (k + 1)))) and c in V \ (PartUnion (V,Mn)) and A64: Ball (c,(3 / (2 |^ (k + 1)))) c= V and not c in union { (union (f . q)) where q is Element of NAT : q <= k } ; Ball (c,(1 / (2 |^ (k + 1)))) c= Ball (c,(3 / (2 |^ (k + 1)))) by PCOMPS_1:1, XREAL_1:72; hence W c= V by A63, A64, XBOOLE_1:1; ::_thesis: verum end; reconsider V = V as set ; take Y = V; ::_thesis: ( Y in FX & X c= Y ) thus Y in FX by A61; ::_thesis: X c= Y thus X c= Y by A60, A62, ZFMISC_1:76; ::_thesis: verum end; end; end; end; hence ex Y being set st ( Y in FX & X c= Y ) ; ::_thesis: verum end; hence GX is_finer_than FX by SETFAM_1:def_2; ::_thesis: GX is locally_finite for x being Point of PT ex W being Subset of PT st ( x in W & W is open & { V where V is Subset of PT : ( V in GX & V meets W ) } is finite ) proof let x be Point of PT; ::_thesis: ex W being Subset of PT st ( x in W & W is open & { V where V is Subset of PT : ( V in GX & V meets W ) } is finite ) reconsider x9 = x as Element of PM by A1, A7, Th4; consider X being Subset of PT such that A65: x in X and A66: X in GX by A50, PCOMPS_1:3; reconsider X = X as Subset of PT ; X is open by A14, A66; then X in Family_open_set PM by A2, A7, PRE_TOPC:def_2; then consider r being Real such that A67: r > 0 and A68: Ball (x9,r) c= X by A65, PCOMPS_1:def_4; consider m being Element of NAT such that A69: 1 / (2 |^ m) <= r by A67, PREPOWER:92; defpred S4[ set ] means X in f . $1; ex n being Element of NAT st S4[n] by A13, A66; then A70: ex n being Nat st S4[n] ; consider k being Nat such that A71: S4[k] and for l being Nat st S4[l] holds k <= l from NAT_1:sch_5(A70); consider W being Subset of PM such that A72: W = Ball (x9,(1 / (2 |^ (((m + 1) + k) + 1)))) ; reconsider W = W as Subset of PT by A1, A7, Th4; A73: { V where V is Subset of PT : ( V in GX & V meets W ) } is finite proof defpred S5[ set , set ] means $1 in f . $2; set NZ = { V where V is Subset of PT : ( V in GX & V meets W ) } ; A74: for p being set st p in { V where V is Subset of PT : ( V in GX & V meets W ) } holds ex n being Element of NAT st S5[p,n] proof let p be set ; ::_thesis: ( p in { V where V is Subset of PT : ( V in GX & V meets W ) } implies ex n being Element of NAT st S5[p,n] ) assume p in { V where V is Subset of PT : ( V in GX & V meets W ) } ; ::_thesis: ex n being Element of NAT st S5[p,n] then ex V being Subset of PT st ( p = V & V in GX & V meets W ) ; hence ex n being Element of NAT st S5[p,n] by A13; ::_thesis: verum end; consider g being Function such that A75: dom g = { V where V is Subset of PT : ( V in GX & V meets W ) } and A76: for y being set st y in { V where V is Subset of PT : ( V in GX & V meets W ) } holds ex n being Element of NAT st ( g . y = n & S5[y,n] & ( for t being Element of NAT st S5[y,t] holds n <= t ) ) from TREES_2:sch_4(A74); A77: rng g c= { i where i is Element of NAT : i < ((m + 1) + k) + 1 } proof let t be set ; :: according to TARSKI:def_3 ::_thesis: ( not t in rng g or t in { i where i is Element of NAT : i < ((m + 1) + k) + 1 } ) assume t in rng g ; ::_thesis: t in { i where i is Element of NAT : i < ((m + 1) + k) + 1 } then consider a being set such that A78: a in dom g and A79: t = g . a by FUNCT_1:def_3; assume A80: not t in { i where i is Element of NAT : i < ((m + 1) + k) + 1 } ; ::_thesis: contradiction A81: ex n being Element of NAT st ( g . a = n & a in f . n & ( for p being Element of NAT st a in f . p holds n <= p ) ) by A75, A76, A78; then reconsider t = t as Element of NAT by A79; consider V being Subset of PT such that A82: a = V and V in GX and A83: V meets W by A75, A78; consider y being set such that A84: y in V and A85: y in W by A83, XBOOLE_0:3; A86: t >= ((m + 1) + k) + 1 by A80; now__::_thesis:_contradiction percases ( t = 0 or t > 0 ) ; suppose t = 0 ; ::_thesis: contradiction hence contradiction by A80; ::_thesis: verum end; suppose t > 0 ; ::_thesis: contradiction then consider l being Nat such that A87: t = l + 1 by NAT_1:6; reconsider l = l as Element of NAT by ORDINAL1:def_12; A88: V in { (union { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in Y \ (PartUnion (Y,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= Y & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } ) where Y is Subset of PM : Y in FX } by A12, A79, A81, A82, A87; ( 2 |^ t >= 2 |^ (((m + 1) + k) + 1) & 2 |^ (((m + 1) + k) + 1) > 0 ) by A86, PREPOWER:6, PREPOWER:93; then A89: 1 / (2 |^ (((m + 1) + k) + 1)) >= 1 / (2 |^ t) by XREAL_1:118; consider Y being Subset of PM such that A90: V = union { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in Y \ (PartUnion (Y,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= Y & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } and Y in FX by A88; reconsider NF = { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in Y \ (PartUnion (Y,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= Y & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } as set ; consider T being set such that A91: y in T and A92: T in NF by A84, A90, TARSKI:def_4; reconsider y = y as Element of PM by A85; consider c being Element of PM such that A93: T = Ball (c,(1 / (2 |^ (l + 1)))) and c in Y \ (PartUnion (Y,Mn)) and Ball (c,(3 / (2 |^ (l + 1)))) c= Y and A94: not c in union { (union (f . q)) where q is Element of NAT : q <= l } by A92; dist (c,y) < 1 / (2 |^ t) by A87, A91, A93, METRIC_1:11; then dist (c,y) < 1 / (2 |^ (((m + 1) + k) + 1)) by A89, XXREAL_0:2; then A95: (dist (c,y)) + (dist (y,x9)) < (1 / (2 |^ (((m + 1) + k) + 1))) + (dist (y,x9)) by XREAL_1:6; A96: for t being Element of NAT st t < l holds not c in union (f . t) proof let t be Element of NAT ; ::_thesis: ( t < l implies not c in union (f . t) ) assume t < l ; ::_thesis: not c in union (f . t) then A97: union (f . t) in { (union (f . q)) where q is Element of NAT : q <= l } ; assume c in union (f . t) ; ::_thesis: contradiction hence contradiction by A94, A97, TARSKI:def_4; ::_thesis: verum end; A98: dist (c,x9) >= 1 / (2 |^ m) proof assume not dist (c,x9) >= 1 / (2 |^ m) ; ::_thesis: contradiction then dist (x9,c) < r by A69, XXREAL_0:2; then c in Ball (x9,r) by METRIC_1:11; then A99: c in union (f . k) by A71, A68, TARSKI:def_4; A100: k <> l proof assume k = l ; ::_thesis: contradiction then union (f . k) in { (union (f . q)) where q is Element of NAT : q <= l } ; hence contradiction by A94, A99, TARSKI:def_4; ::_thesis: verum end; ( l >= k + (m + 1) & k + (m + 1) >= k ) by A86, A87, NAT_1:11, XREAL_1:6; then k <= l by XXREAL_0:2; then ( k in NAT & k < l ) by A100, ORDINAL1:def_12, XXREAL_0:1; hence contradiction by A96, A99; ::_thesis: verum end; (dist (c,y)) + (dist (y,x9)) >= dist (c,x9) by METRIC_1:4; then (dist (c,y)) + (dist (y,x9)) >= 1 / (2 |^ m) by A98, XXREAL_0:2; then (1 / (2 |^ (((m + 1) + k) + 1))) + (dist (y,x9)) > 1 / (2 |^ m) by A95, XXREAL_0:2; then A101: dist (y,x9) >= (1 / (2 |^ m)) - (1 / (2 |^ (((m + 1) + k) + 1))) by XREAL_1:19; (2 |^ (1 + k)) * 2 >= 2 by PREPOWER:11, XREAL_1:151; then A102: ((2 |^ (1 + k)) * 2) - 1 >= 2 - 1 by XREAL_1:9; 2 |^ ((1 + k) + 1) <> 0 by PREPOWER:5; then (1 / (2 |^ m)) - (1 / (2 |^ (((m + 1) + k) + 1))) = ((1 * (2 |^ ((1 + k) + 1))) / ((2 |^ m) * (2 |^ ((1 + k) + 1)))) - (1 / (2 |^ (((m + 1) + k) + 1))) by XCMPLX_1:91 .= ((1 * (2 |^ ((1 + k) + 1))) / (2 |^ (m + ((1 + k) + 1)))) - (1 / (2 |^ (((m + 1) + k) + 1))) by NEWTON:8 .= (((2 |^ (1 + k)) * 2) / (2 |^ (((m + 1) + k) + 1))) - (1 / (2 |^ (((m + 1) + k) + 1))) by NEWTON:6 .= (((2 |^ (1 + k)) * 2) - 1) / (2 |^ (((m + 1) + k) + 1)) by XCMPLX_1:120 ; then (1 / (2 |^ m)) - (1 / (2 |^ (((m + 1) + k) + 1))) >= 1 / (2 |^ (((m + 1) + k) + 1)) by A102, XREAL_1:72; then dist (y,x9) >= 1 / (2 |^ (((m + 1) + k) + 1)) by A101, XXREAL_0:2; hence contradiction by A72, A85, METRIC_1:11; ::_thesis: verum end; end; end; hence contradiction ; ::_thesis: verum end; for x1, x2 being set st x1 in dom g & x2 in dom g & g . x1 = g . x2 holds x1 = x2 proof let x1, x2 be set ; ::_thesis: ( x1 in dom g & x2 in dom g & g . x1 = g . x2 implies x1 = x2 ) assume that A103: x1 in dom g and A104: x2 in dom g and A105: g . x1 = g . x2 ; ::_thesis: x1 = x2 ex V2 being Subset of PT st ( x2 = V2 & V2 in GX & V2 meets W ) by A75, A104; then consider w2 being set such that A106: w2 in W and A107: w2 in x2 by XBOOLE_0:3; consider n1 being Element of NAT such that A108: g . x1 = n1 and A109: x1 in f . n1 and for t being Element of NAT st x1 in f . t holds n1 <= t by A75, A76, A103; ex V1 being Subset of PT st ( x1 = V1 & V1 in GX & V1 meets W ) by A75, A103; then consider w1 being set such that A110: w1 in W and A111: w1 in x1 by XBOOLE_0:3; assume A112: x1 <> x2 ; ::_thesis: contradiction reconsider w1 = w1, w2 = w2 as Element of PM by A110, A106; A113: ex n2 being Element of NAT st ( g . x2 = n2 & x2 in f . n2 & ( for t being Element of NAT st x2 in f . t holds n2 <= t ) ) by A75, A76, A104; now__::_thesis:_contradiction percases ( n1 = 0 or n1 > 0 ) ; supposeA114: n1 = 0 ; ::_thesis: contradiction (m + k) + 1 >= 1 by NAT_1:11; then 2 |^ ((m + 1) + k) >= 2 |^ 1 by PREPOWER:93; then 2 |^ ((m + 1) + k) >= 2 by NEWTON:5; then A115: 1 / (2 |^ ((m + 1) + k)) <= 1 / 2 by XREAL_1:118; A116: 2 / (2 |^ (((m + 1) + k) + 1)) = (1 * 2) / ((2 |^ ((m + 1) + k)) * 2) by NEWTON:6 .= 1 / (2 |^ ((m + 1) + k)) by XCMPLX_1:91 ; ((1 / 2) + (1 / (2 |^ (((m + 1) + k) + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2)) = ((1 + 1) / 2) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (((m + 1) + k) + 1)))) .= (2 / 2) + (2 / (2 |^ (((m + 1) + k) + 1))) by XCMPLX_1:62 ; then (((1 / 2) + (1 / (2 |^ (((m + 1) + k) + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) - (2 / 2) = 1 / (2 |^ ((m + 1) + k)) by A116; then A117: ((1 / 2) + (1 / (2 |^ (((m + 1) + k) + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2)) <= (2 / 2) + (1 / 2) by A115, XREAL_1:20; A118: Mn is_connected_in FX by A21, WELLORD1:def_5; A119: dist (x9,w2) < 1 / (2 |^ (((m + 1) + k) + 1)) by A72, A106, METRIC_1:11; consider M1 being Subset of PM such that A120: x1 = union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in M1 \ (PartUnion (M1,Mn)) & Ball (c,(3 / 2)) c= M1 ) } and A121: M1 in FX by A11, A109, A114; consider k1 being set such that A122: w1 in k1 and A123: k1 in { (Ball (c,(1 / 2))) where c is Element of PM : ( c in M1 \ (PartUnion (M1,Mn)) & Ball (c,(3 / 2)) c= M1 ) } by A111, A120, TARSKI:def_4; consider c1 being Element of PM such that A124: k1 = Ball (c1,(1 / 2)) and A125: c1 in M1 \ (PartUnion (M1,Mn)) and A126: Ball (c1,(3 / 2)) c= M1 by A123; A127: dist (c1,w1) < 1 / 2 by A122, A124, METRIC_1:11; consider M2 being Subset of PM such that A128: x2 = union { (Ball (c,(1 / 2))) where c is Element of PM : ( c in M2 \ (PartUnion (M2,Mn)) & Ball (c,(3 / 2)) c= M2 ) } and A129: M2 in FX by A11, A105, A108, A113, A114; consider k2 being set such that A130: w2 in k2 and A131: k2 in { (Ball (c,(1 / 2))) where c is Element of PM : ( c in M2 \ (PartUnion (M2,Mn)) & Ball (c,(3 / 2)) c= M2 ) } by A107, A128, TARSKI:def_4; consider c2 being Element of PM such that A132: k2 = Ball (c2,(1 / 2)) and A133: c2 in M2 \ (PartUnion (M2,Mn)) and A134: Ball (c2,(3 / 2)) c= M2 by A131; ( dist (x9,c2) <= (dist (x9,w2)) + (dist (w2,c2)) & dist (c1,x9) <= (dist (c1,w1)) + (dist (w1,x9)) ) by METRIC_1:4; then A135: (dist (c1,x9)) + (dist (x9,c2)) <= ((dist (c1,w1)) + (dist (w1,x9))) + ((dist (x9,w2)) + (dist (w2,c2))) by XREAL_1:7; dist (c1,c2) <= (dist (c1,x9)) + (dist (x9,c2)) by METRIC_1:4; then dist (c1,c2) <= (dist (c1,w1)) + ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) by A135, XXREAL_0:2; then (dist (c1,c2)) - ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) <= dist (c1,w1) by XREAL_1:20; then (dist (c1,c2)) - ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) < 1 / 2 by A127, XXREAL_0:2; then dist (c1,c2) < (1 / 2) + ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) by XREAL_1:19; then dist (c1,c2) < (dist (w1,x9)) + ((1 / 2) + ((dist (x9,w2)) + (dist (w2,c2)))) ; then A136: (dist (c1,c2)) - ((1 / 2) + ((dist (x9,w2)) + (dist (w2,c2)))) < dist (w1,x9) by XREAL_1:19; dist (x9,w1) < 1 / (2 |^ (((m + 1) + k) + 1)) by A72, A110, METRIC_1:11; then (dist (c1,c2)) - ((1 / 2) + ((dist (x9,w2)) + (dist (w2,c2)))) < 1 / (2 |^ (((m + 1) + k) + 1)) by A136, XXREAL_0:2; then dist (c1,c2) < (1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / 2) + ((dist (x9,w2)) + (dist (w2,c2)))) by XREAL_1:19; then dist (c1,c2) < (dist (x9,w2)) + ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) ; then (dist (c1,c2)) - ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) < dist (x9,w2) by XREAL_1:19; then (dist (c1,c2)) - ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) < 1 / (2 |^ (((m + 1) + k) + 1)) by A119, XXREAL_0:2; then dist (c1,c2) < (1 / (2 |^ (((m + 1) + k) + 1))) + ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) by XREAL_1:19; then dist (c1,c2) < (dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) ; then A137: (dist (c1,c2)) - ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) < dist (w2,c2) by XREAL_1:19; dist (c2,w2) < 1 / 2 by A130, A132, METRIC_1:11; then (dist (c1,c2)) - ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) < 1 / 2 by A137, XXREAL_0:2; then dist (c1,c2) < (1 / 2) + ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / 2))) by XREAL_1:19; then A138: dist (c1,c2) < 3 / 2 by A117, XXREAL_0:2; then A139: c1 in Ball (c2,(3 / 2)) by METRIC_1:11; A140: M1 <> M2 by A112, A120, A128; A141: c2 in Ball (c1,(3 / 2)) by A138, METRIC_1:11; now__::_thesis:_contradiction percases ( [M1,M2] in Mn or [M2,M1] in Mn ) by A121, A129, A118, A140, RELAT_2:def_6; suppose [M1,M2] in Mn ; ::_thesis: contradiction then M1 in Mn -Seg M2 by A140, WELLORD1:1; then c2 in PartUnion (M2,Mn) by A126, A141, TARSKI:def_4; hence contradiction by A133, XBOOLE_0:def_5; ::_thesis: verum end; suppose [M2,M1] in Mn ; ::_thesis: contradiction then M2 in Mn -Seg M1 by A140, WELLORD1:1; then c1 in PartUnion (M1,Mn) by A134, A139, TARSKI:def_4; hence contradiction by A125, XBOOLE_0:def_5; ::_thesis: verum end; end; end; hence contradiction ; ::_thesis: verum end; suppose n1 > 0 ; ::_thesis: contradiction then consider l being Nat such that A142: n1 = l + 1 by NAT_1:6; reconsider l = l as Element of NAT by ORDINAL1:def_12; A143: x1 in { (union { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in M1 \ (PartUnion (M1,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= M1 & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } ) where M1 is Subset of PM : M1 in FX } by A12, A109, A142; A144: dist (x9,w2) < 1 / (2 |^ (((m + 1) + k) + 1)) by A72, A106, METRIC_1:11; A145: x2 in { (union { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in M2 \ (PartUnion (M2,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= M2 & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } ) where M2 is Subset of PM : M2 in FX } by A12, A105, A108, A113, A142; A146: ((1 / (2 |^ (l + 1))) + (1 / (2 |^ (((m + 1) + k) + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1)))) = ((1 / (2 |^ (l + 1))) + (1 / (2 |^ (l + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (((m + 1) + k) + 1)))) .= ((1 + 1) / (2 |^ (l + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (((m + 1) + k) + 1)))) by XCMPLX_1:62 .= (2 / (2 |^ (l + 1))) + (2 / (2 |^ (((m + 1) + k) + 1))) by XCMPLX_1:62 ; n1 in rng g by A103, A108, FUNCT_1:def_3; then n1 in { i where i is Element of NAT : i < ((m + 1) + k) + 1 } by A77; then A147: ex i being Element of NAT st ( n1 = i & i < ((m + 1) + k) + 1 ) ; then consider h being Nat such that A148: ((m + 1) + k) + 1 = (l + 1) + h by A142, NAT_1:10; h <> 0 by A142, A147, A148; then consider i being Nat such that A149: h = i + 1 by NAT_1:6; (l + 1) + i >= l + 1 by NAT_1:11; then ( 2 |^ (l + 1) > 0 & 2 |^ ((l + 1) + i) >= 2 |^ (l + 1) ) by PREPOWER:6, PREPOWER:93; then A150: 1 / (2 |^ ((l + 1) + i)) <= 1 / (2 |^ (l + 1)) by XREAL_1:118; 2 / (2 |^ (((m + 1) + k) + 1)) = (1 * 2) / ((2 |^ ((l + 1) + i)) * 2) by A148, A149, NEWTON:6 .= 1 / (2 |^ ((l + 1) + i)) by XCMPLX_1:91 ; then (((1 / (2 |^ (l + 1))) + (1 / (2 |^ (((m + 1) + k) + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) - (2 / (2 |^ (l + 1))) = 1 / (2 |^ ((l + 1) + i)) by A146; then ((1 / (2 |^ (l + 1))) + (1 / (2 |^ (((m + 1) + k) + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1)))) <= (2 / (2 |^ (l + 1))) + (1 / (2 |^ (l + 1))) by A150, XREAL_1:20; then A151: ((1 / (2 |^ (l + 1))) + (1 / (2 |^ (((m + 1) + k) + 1)))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1)))) <= (2 + 1) / (2 |^ (l + 1)) by XCMPLX_1:62; A152: Mn is_connected_in FX by A21, WELLORD1:def_5; consider M1 being Subset of PM such that A153: x1 = union { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in M1 \ (PartUnion (M1,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= M1 & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } and A154: M1 in FX by A143; reconsider NF = { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in M1 \ (PartUnion (M1,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= M1 & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } as set ; consider k1 being set such that A155: w1 in k1 and A156: k1 in NF by A111, A153, TARSKI:def_4; consider c1 being Element of PM such that A157: k1 = Ball (c1,(1 / (2 |^ (l + 1)))) and A158: c1 in M1 \ (PartUnion (M1,Mn)) and A159: Ball (c1,(3 / (2 |^ (l + 1)))) c= M1 and not c1 in union { (union (f . q)) where q is Element of NAT : q <= l } by A156; A160: dist (c1,w1) < 1 / (2 |^ (l + 1)) by A155, A157, METRIC_1:11; consider M2 being Subset of PM such that A161: x2 = union { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in M2 \ (PartUnion (M2,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= M2 & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } and A162: M2 in FX by A145; A163: M1 <> M2 by A112, A153, A161; reconsider NF = { (Ball (c,(1 / (2 |^ (l + 1))))) where c is Element of PM : ( c in M2 \ (PartUnion (M2,Mn)) & Ball (c,(3 / (2 |^ (l + 1)))) c= M2 & not c in union { (union (f . q)) where q is Element of NAT : q <= l } ) } as set ; consider k2 being set such that A164: w2 in k2 and A165: k2 in NF by A107, A161, TARSKI:def_4; consider c2 being Element of PM such that A166: k2 = Ball (c2,(1 / (2 |^ (l + 1)))) and A167: c2 in M2 \ (PartUnion (M2,Mn)) and A168: Ball (c2,(3 / (2 |^ (l + 1)))) c= M2 and not c2 in union { (union (f . q)) where q is Element of NAT : q <= l } by A165; ( dist (x9,c2) <= (dist (x9,w2)) + (dist (w2,c2)) & dist (c1,x9) <= (dist (c1,w1)) + (dist (w1,x9)) ) by METRIC_1:4; then A169: (dist (c1,x9)) + (dist (x9,c2)) <= ((dist (c1,w1)) + (dist (w1,x9))) + ((dist (x9,w2)) + (dist (w2,c2))) by XREAL_1:7; dist (c1,c2) <= (dist (c1,x9)) + (dist (x9,c2)) by METRIC_1:4; then dist (c1,c2) <= (dist (c1,w1)) + ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) by A169, XXREAL_0:2; then (dist (c1,c2)) - ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) <= dist (c1,w1) by XREAL_1:20; then (dist (c1,c2)) - ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) < 1 / (2 |^ (l + 1)) by A160, XXREAL_0:2; then dist (c1,c2) < (1 / (2 |^ (l + 1))) + ((dist (w1,x9)) + ((dist (x9,w2)) + (dist (w2,c2)))) by XREAL_1:19; then dist (c1,c2) < (dist (w1,x9)) + ((1 / (2 |^ (l + 1))) + ((dist (x9,w2)) + (dist (w2,c2)))) ; then A170: (dist (c1,c2)) - ((1 / (2 |^ (l + 1))) + ((dist (x9,w2)) + (dist (w2,c2)))) < dist (w1,x9) by XREAL_1:19; dist (x9,w1) < 1 / (2 |^ (((m + 1) + k) + 1)) by A72, A110, METRIC_1:11; then (dist (c1,c2)) - ((1 / (2 |^ (l + 1))) + ((dist (x9,w2)) + (dist (w2,c2)))) < 1 / (2 |^ (((m + 1) + k) + 1)) by A170, XXREAL_0:2; then dist (c1,c2) < (1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (l + 1))) + ((dist (x9,w2)) + (dist (w2,c2)))) by XREAL_1:19; then dist (c1,c2) < (dist (x9,w2)) + ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) ; then (dist (c1,c2)) - ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) < dist (x9,w2) by XREAL_1:19; then (dist (c1,c2)) - ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) < 1 / (2 |^ (((m + 1) + k) + 1)) by A144, XXREAL_0:2; then dist (c1,c2) < (1 / (2 |^ (((m + 1) + k) + 1))) + ((dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) by XREAL_1:19; then dist (c1,c2) < (dist (w2,c2)) + ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) ; then A171: (dist (c1,c2)) - ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) < dist (w2,c2) by XREAL_1:19; dist (c2,w2) < 1 / (2 |^ (l + 1)) by A164, A166, METRIC_1:11; then (dist (c1,c2)) - ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) < 1 / (2 |^ (l + 1)) by A171, XXREAL_0:2; then dist (c1,c2) < (1 / (2 |^ (l + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + ((1 / (2 |^ (((m + 1) + k) + 1))) + (1 / (2 |^ (l + 1))))) by XREAL_1:19; then A172: dist (c1,c2) < 3 / (2 |^ (l + 1)) by A151, XXREAL_0:2; then A173: c1 in Ball (c2,(3 / (2 |^ (l + 1)))) by METRIC_1:11; A174: c2 in Ball (c1,(3 / (2 |^ (l + 1)))) by A172, METRIC_1:11; now__::_thesis:_contradiction percases ( [M1,M2] in Mn or [M2,M1] in Mn ) by A154, A162, A152, A163, RELAT_2:def_6; suppose [M1,M2] in Mn ; ::_thesis: contradiction then M1 in Mn -Seg M2 by A163, WELLORD1:1; then c2 in PartUnion (M2,Mn) by A159, A174, TARSKI:def_4; hence contradiction by A167, XBOOLE_0:def_5; ::_thesis: verum end; suppose [M2,M1] in Mn ; ::_thesis: contradiction then M2 in Mn -Seg M1 by A163, WELLORD1:1; then c1 in PartUnion (M1,Mn) by A168, A173, TARSKI:def_4; hence contradiction by A158, XBOOLE_0:def_5; ::_thesis: verum end; end; end; hence contradiction ; ::_thesis: verum end; end; end; hence contradiction ; ::_thesis: verum end; then g is one-to-one by FUNCT_1:def_4; then A175: { V where V is Subset of PT : ( V in GX & V meets W ) } , rng g are_equipotent by A75, WELLORD2:def_4; { i where i is Element of NAT : i < ((m + 1) + k) + 1 } is finite proof { i where i is Element of NAT : i < ((m + 1) + k) + 1 } c= {0} \/ (Seg (((m + 1) + k) + 1)) proof let x be set ; :: according to TARSKI:def_3 ::_thesis: ( not x in { i where i is Element of NAT : i < ((m + 1) + k) + 1 } or x in {0} \/ (Seg (((m + 1) + k) + 1)) ) assume x in { i where i is Element of NAT : i < ((m + 1) + k) + 1 } ; ::_thesis: x in {0} \/ (Seg (((m + 1) + k) + 1)) then A176: ex i being Element of NAT st ( x = i & i < ((m + 1) + k) + 1 ) ; then reconsider x1 = x as Element of NAT ; now__::_thesis:_(_x1_in_{0}_or_x1_in_Seg_(((m_+_1)_+_k)_+_1)_) percases ( x1 = 0 or x1 > 0 ) ; suppose x1 = 0 ; ::_thesis: ( x1 in {0} or x1 in Seg (((m + 1) + k) + 1) ) hence ( x1 in {0} or x1 in Seg (((m + 1) + k) + 1) ) by TARSKI:def_1; ::_thesis: verum end; suppose x1 > 0 ; ::_thesis: ( x1 in {0} or x1 in Seg (((m + 1) + k) + 1) ) then ex l being Nat st x1 = l + 1 by NAT_1:6; then x1 >= 1 by NAT_1:11; hence ( x1 in {0} or x1 in Seg (((m + 1) + k) + 1) ) by A176, FINSEQ_1:1; ::_thesis: verum end; end; end; hence x in {0} \/ (Seg (((m + 1) + k) + 1)) by XBOOLE_0:def_3; ::_thesis: verum end; hence { i where i is Element of NAT : i < ((m + 1) + k) + 1 } is finite ; ::_thesis: verum end; hence { V where V is Subset of PT : ( V in GX & V meets W ) } is finite by A77, A175, CARD_1:38; ::_thesis: verum end; 2 |^ (((m + 1) + k) + 1) > 0 by PREPOWER:6; then A177: 1 / (2 |^ (((m + 1) + k) + 1)) > 0 by XREAL_1:139; W in the topology of PT by A2, A7, A72, PCOMPS_1:29; then W is open by PRE_TOPC:def_2; hence ex W being Subset of PT st ( x in W & W is open & { V where V is Subset of PT : ( V in GX & V meets W ) } is finite ) by A177, A72, A73, TBSP_1:11; ::_thesis: verum end; hence GX is locally_finite by PCOMPS_1:def_1; ::_thesis: verum end; theorem :: PCOMPS_2:7 for PT being non empty TopSpace st PT is metrizable holds PT is paracompact proof let PT be non empty TopSpace; ::_thesis: ( PT is metrizable implies PT is paracompact ) assume PT is metrizable ; ::_thesis: PT is paracompact then for FX being Subset-Family of PT st FX is Cover of PT & FX is open holds ex GX being Subset-Family of PT st ( GX is open & GX is Cover of PT & GX is_finer_than FX & GX is locally_finite ) by Th6; hence PT is paracompact by PCOMPS_1:def_3; ::_thesis: verum end;