Definition 2.16 .

A B 𝐡 B italic_B -module M 𝑀 M italic_M is called a Poisson module if it is endowed with a Lie algebra action { , } : B βŠ— M β†’ M fragments fragments { , } : B tensor-product M β†’ M \{{,\}}:B\otimes M\to M { , } : italic_B βŠ— italic_M β†’ italic_M that satisfies the Leibniz rules:

{ a , b ⁒ m } = { a , b } ⁒ m + b ⁒ { a , m } , { a ⁒ b , m } = a ⁒ { b , m } + b ⁒ { a , m } . formulae-sequence π‘Ž 𝑏 π‘š π‘Ž 𝑏 π‘š 𝑏 π‘Ž π‘š π‘Ž 𝑏 π‘š π‘Ž 𝑏 π‘š 𝑏 π‘Ž π‘š \{{a,bm\}}=\{{a,b\}}m+b\{{a,m\}},\ \{{ab,m\}}=a\{{b,m\}}+b\{{a,m\}}. { italic_a , italic_b italic_m } = { italic_a , italic_b } italic_m + italic_b { italic_a , italic_m } , { italic_a italic_b , italic_m } = italic_a { italic_b , italic_m } + italic_b { italic_a , italic_m } .

Definition 4.2

An ( Ξ΅ ) πœ€ \left(\varepsilon\right) ( italic_Ξ΅ ) -almost paracontact metric structure ( Ο† , ΞΎ , Ξ· , g , Ξ΅ ) πœ‘ πœ‰ πœ‚ 𝑔 πœ€ (\varphi,\xi,\eta,g,\varepsilon) ( italic_Ο† , italic_ΞΎ , italic_Ξ· , italic_g , italic_Ξ΅ ) is called an ( Ξ΅ ) πœ€ (\varepsilon) ( italic_Ξ΅ ) - s 𝑠 s italic_s -paracontact metric structure if

βˆ‡ ⁑ ΞΎ = Ξ΅ ⁒ Ο† . βˆ‡ πœ‰ πœ€ πœ‘ \nabla\xi=\varepsilon\varphi. βˆ‡ italic_ΞΎ = italic_Ξ΅ italic_Ο† . (4.6)

A manifold equipped with an ( Ξ΅ ) πœ€ (\varepsilon) ( italic_Ξ΅ ) - s 𝑠 s italic_s -paracontact structure is said to be ( Ξ΅ ) πœ€ (\varepsilon) ( italic_Ξ΅ ) - s 𝑠 s italic_s -paracontact metric manifold .


Definition 2.3 .

Let Ο€ πœ‹ \pi italic_Ο€ be a group. A Ο€ πœ‹ \pi italic_Ο€ -module is a pair ( A , Ο• ) 𝐴 italic-Ο• (A,\phi) ( italic_A , italic_Ο• ) where A 𝐴 A italic_A is an abelian group and Ο• : Ο€ β†’ A ⁒ u ⁒ t ⁒ ( A ) normal-: italic-Ο• normal-β†’ πœ‹ 𝐴 𝑒 𝑑 𝐴 \phi\colon\pi\rightarrow Aut(A) italic_Ο• : italic_Ο€ β†’ italic_A italic_u italic_t ( italic_A ) a group homomorphism. A map of Ο€ πœ‹ \pi italic_Ο€ -modules f : ( A , Ο• ) β†’ ( A β€² , Ο• β€² ) normal-: 𝑓 normal-β†’ 𝐴 italic-Ο• superscript 𝐴 normal-β€² superscript italic-Ο• normal-β€² f\colon(A,\phi)\rightarrow(A^{\prime},\phi^{\prime}) italic_f : ( italic_A , italic_Ο• ) β†’ ( italic_A start_POSTSUPERSCRIPT β€² end_POSTSUPERSCRIPT , italic_Ο• start_POSTSUPERSCRIPT β€² end_POSTSUPERSCRIPT ) is a group homomorphism f : A β†’ A β€² normal-: 𝑓 normal-β†’ 𝐴 superscript 𝐴 normal-β€² f\colon A\rightarrow A^{\prime} italic_f : italic_A β†’ italic_A start_POSTSUPERSCRIPT β€² end_POSTSUPERSCRIPT such that

f ⁒ ( Ο• ⁒ ( x ) ⁒ a ) = Ο• β€² ⁒ ( x ) ⁒ f ⁒ ( a ) 𝑓 italic-Ο• π‘₯ π‘Ž superscript italic-Ο• β€² π‘₯ 𝑓 π‘Ž f(\phi(x)a)=\phi^{\prime}(x)f(a) italic_f ( italic_Ο• ( italic_x ) italic_a ) = italic_Ο• start_POSTSUPERSCRIPT β€² end_POSTSUPERSCRIPT ( italic_x ) italic_f ( italic_a )

for all x ∈ Ο€ π‘₯ πœ‹ x\in\pi italic_x ∈ italic_Ο€ and a ∈ A π‘Ž 𝐴 a\in A italic_a ∈ italic_A . The category of Ο€ πœ‹ \pi italic_Ο€ -modules is denoted by Ο€ πœ‹ \pi italic_Ο€ -mod.


Definition 28

A G 𝐺 G italic_G -Hilbert A 𝐴 A italic_A -module is a Hilbert A 𝐴 A italic_A -module β„‹ β„‹ {\cal H} caligraphic_H with a given continuous action

G Γ— β„‹ 𝐺 β„‹ \displaystyle G\times{\cal H} italic_G Γ— caligraphic_H β†’ β†’ \displaystyle\rightarrow β†’ β„‹ β„‹ \displaystyle{\cal H} caligraphic_H
( g , v ) 𝑔 𝑣 \displaystyle(g,v) ( italic_g , italic_v ) ↦ maps-to \displaystyle\mapsto ↦ g ⁒ v 𝑔 𝑣 \displaystyle gv italic_g italic_v

such that

  1. 1.

    g ⁒ ( u + v ) = g ⁒ u + g ⁒ v 𝑔 𝑒 𝑣 𝑔 𝑒 𝑔 𝑣 g(u+v)=gu+gv italic_g ( italic_u + italic_v ) = italic_g italic_u + italic_g italic_v ,

  2. 2.

    g ⁒ ( u ⁒ a ) = ( g ⁒ u ) ⁒ ( g ⁒ a ) 𝑔 𝑒 π‘Ž 𝑔 𝑒 𝑔 π‘Ž g(ua)=(gu)(ga) italic_g ( italic_u italic_a ) = ( italic_g italic_u ) ( italic_g italic_a ) ,

  3. 3.

    ⟨ g ⁒ u , g ⁒ v ⟩ = g ⁒ ⟨ u , v ⟩ 𝑔 𝑒 𝑔 𝑣 𝑔 𝑒 𝑣 \langle gu,gv\rangle=g\langle u,v\rangle ⟨ italic_g italic_u , italic_g italic_v ⟩ = italic_g ⟨ italic_u , italic_v ⟩ ,

for all g ∈ G 𝑔 𝐺 g\in G italic_g ∈ italic_G , u , v ∈ β„‹ 𝑒 𝑣 β„‹ u,v\in{\cal H} italic_u , italic_v ∈ caligraphic_H , a ∈ A π‘Ž 𝐴 a\in A italic_a ∈ italic_A .


Definition 3.1 .

The quaternions ( ℍ ℍ \mathbb{H} blackboard_H for short after Hamilton, their discoverer) are the elements of the vector space ℝ 4 superscript ℝ 4 {\mathbb{R}}^{4} blackboard_R start_POSTSUPERSCRIPT 4 end_POSTSUPERSCRIPT with basis { 1 , i , j , k } 1 𝑖 𝑗 π‘˜ \{1,i,j,k\} { 1 , italic_i , italic_j , italic_k } . Addition is defined by vector addition, and multiplication follows the rules for scalar multiplication by real numbers, and:

i 2 = j 2 = k 2 = - 1 , superscript 𝑖 2 superscript 𝑗 2 superscript π‘˜ 2 1 i^{2}=j^{2}=k^{2}=-1, italic_i start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT = italic_j start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT = italic_k start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT = - 1 ,
i ⁒ j = k , j ⁒ k = i , k ⁒ i = j , formulae-sequence 𝑖 𝑗 π‘˜ formulae-sequence 𝑗 π‘˜ 𝑖 π‘˜ 𝑖 𝑗 ij=k,\quad jk=i,\quad ki=j, italic_i italic_j = italic_k , italic_j italic_k = italic_i , italic_k italic_i = italic_j ,

and

j ⁒ i = - k , k ⁒ j = - i , i ⁒ k = - j . formulae-sequence 𝑗 𝑖 π‘˜ formulae-sequence π‘˜ 𝑗 𝑖 𝑖 π‘˜ 𝑗 ji=-k,\quad kj=-i,\quad ik=-j. italic_j italic_i = - italic_k , italic_k italic_j = - italic_i , italic_i italic_k = - italic_j .

Definition 3

The non-negative function E 𝐸 E italic_E is a pseudo-measure for the LOCC π’ž 𝒳 subscript π’ž 𝒳 \mathcal{C}_{\mathcal{X}} caligraphic_C start_POSTSUBSCRIPT caligraphic_X end_POSTSUBSCRIPT , if:

( i β€² ) Οƒ ⁒ separable β‡’ E ⁒ ( Οƒ ) = 0 , superscript i β€² 𝜎 separable β‡’ 𝐸 𝜎 0 \displaystyle{\rm(i^{\prime})}\quad\sigma\mbox{ separable}\quad\Rightarrow% \quad E(\sigma)=0, ( roman_i start_POSTSUPERSCRIPT β€² end_POSTSUPERSCRIPT ) italic_Οƒ separable β‡’ italic_E ( italic_Οƒ ) = 0 ,
( ii ) βˆ€ Ξ› ∈ π’ž 𝒳 : E ⁒ ( ρ ) β‰₯ E ⁒ ( Ξ› ⁒ ( ρ ) tr ⁒ Ξ› ⁒ ( ρ ) ) . : ii for-all Ξ› subscript π’ž 𝒳 𝐸 𝜌 𝐸 Ξ› 𝜌 tr Ξ› 𝜌 \displaystyle{\rm(ii)}\quad\forall\Lambda\in\mathcal{C}_{\mathcal{X}}:E(\rho)% \geq E\left(\frac{\Lambda(\rho)}{{\rm tr}\,\Lambda(\rho)}\right). ( roman_ii ) βˆ€ roman_Ξ› ∈ caligraphic_C start_POSTSUBSCRIPT caligraphic_X end_POSTSUBSCRIPT : italic_E ( italic_ρ ) β‰₯ italic_E ( divide start_ARG roman_Ξ› ( italic_ρ ) end_ARG start_ARG roman_tr roman_Ξ› ( italic_ρ ) end_ARG ) .

Definition 2.2 .

Suppose G 𝐺 G italic_G is a locally compact Hausdorff groupoid and H 𝐻 H italic_H is a closed subgroupoid with a Haar system. Let X = s - 1 ⁒ ( H ( 0 ) ) 𝑋 superscript 𝑠 1 superscript 𝐻 0 X=s^{-1}(H^{(0)}) italic_X = italic_s start_POSTSUPERSCRIPT - 1 end_POSTSUPERSCRIPT ( italic_H start_POSTSUPERSCRIPT ( 0 ) end_POSTSUPERSCRIPT ) . We define the imprimitivity groupoid G H superscript 𝐺 𝐻 G^{H} italic_G start_POSTSUPERSCRIPT italic_H end_POSTSUPERSCRIPT to be the quotient of X * X = { ( Ξ³ , Ξ· ) : s ⁒ ( Ξ³ ) = s ⁒ ( Ξ· ) } 𝑋 𝑋 conditional-set 𝛾 πœ‚ 𝑠 𝛾 𝑠 πœ‚ X*X=\{(\gamma,\eta):s(\gamma)=s(\eta)\} italic_X * italic_X = { ( italic_Ξ³ , italic_Ξ· ) : italic_s ( italic_Ξ³ ) = italic_s ( italic_Ξ· ) } by H 𝐻 H italic_H where H 𝐻 H italic_H acts diagonally via right translation. We give G H superscript 𝐺 𝐻 G^{H} italic_G start_POSTSUPERSCRIPT italic_H end_POSTSUPERSCRIPT a groupoid structure with the operations

[ Ξ³ , Ξ· ] ⁒ [ Ξ· , ΞΆ ] = [ Ξ³ , ΞΆ ] , and [ Ξ³ , Ξ· ] - 1 = [ Ξ· , Ξ³ ] . formulae-sequence 𝛾 πœ‚ πœ‚ 𝜁 𝛾 𝜁 and superscript 𝛾 πœ‚ 1 πœ‚ 𝛾 [\gamma,\eta][\eta,\zeta]=[\gamma,\zeta],\quad\text{and}\quad[\gamma,\eta]^{-1% }=[\eta,\gamma]. [ italic_Ξ³ , italic_Ξ· ] [ italic_Ξ· , italic_ΞΆ ] = [ italic_Ξ³ , italic_ΞΆ ] , and [ italic_Ξ³ , italic_Ξ· ] start_POSTSUPERSCRIPT - 1 end_POSTSUPERSCRIPT = [ italic_Ξ· , italic_Ξ³ ] .

Definition 2.1 .

A binary Hermitian form over F 𝐹 F italic_F is a map Ο• : F 2 β†’ β„š : italic-Ο• β†’ superscript 𝐹 2 β„š \phi:F^{2}\to\mathbb{Q} italic_Ο• : italic_F start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT β†’ blackboard_Q of the form

Ο• ⁒ ( x , y ) = a ⁒ x ⁒ x Β― + b ⁒ x ⁒ y Β― + b Β― ⁒ x Β― ⁒ y + c ⁒ y ⁒ y Β― , italic-Ο• π‘₯ 𝑦 π‘Ž π‘₯ Β― π‘₯ 𝑏 π‘₯ Β― 𝑦 Β― 𝑏 Β― π‘₯ 𝑦 𝑐 𝑦 Β― 𝑦 \phi(x,y)=ax\bar{x}+bx\bar{y}+\bar{b}\bar{x}y+cy\bar{y}, italic_Ο• ( italic_x , italic_y ) = italic_a italic_x Β― start_ARG italic_x end_ARG + italic_b italic_x Β― start_ARG italic_y end_ARG + Β― start_ARG italic_b end_ARG Β― start_ARG italic_x end_ARG italic_y + italic_c italic_y Β― start_ARG italic_y end_ARG ,

where a , c ∈ β„š π‘Ž 𝑐 β„š a,c\in\mathbb{Q} italic_a , italic_c ∈ blackboard_Q and b ∈ F 𝑏 𝐹 b\in F italic_b ∈ italic_F such that Ο• italic-Ο• \phi italic_Ο• is positive definite.