Definition 1.4 .

(PZ-equivalence) Two open projections p , q P o ( A * * ) 𝑝 𝑞 subscript 𝑃 𝑜 superscript 𝐴 absent p,q\in P_{o}(A^{**}) italic_p , italic_q ∈ italic_P start_POSTSUBSCRIPT italic_o end_POSTSUBSCRIPT ( italic_A start_POSTSUPERSCRIPT * * end_POSTSUPERSCRIPT ) are said to be PZ-equivalent, p 𝑃𝑍 q subscript similar-to 𝑃𝑍 𝑝 𝑞 p\sim_{\text{PZ}}q italic_p ∼ start_POSTSUBSCRIPT PZ end_POSTSUBSCRIPT italic_q in symbols, if there exists a partial isometry v A * * 𝑣 superscript 𝐴 absent v\in A^{**} italic_v ∈ italic_A start_POSTSUPERSCRIPT * * end_POSTSUPERSCRIPT such that

p = v * v , q = v v * , formulae-sequence 𝑝 superscript 𝑣 𝑣 𝑞 𝑣 superscript 𝑣 p=v^{*}v,\qquad q=vv^{*}, italic_p = italic_v start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT italic_v , italic_q = italic_v italic_v start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT ,

and

v A p A , v * A q A . formulae-sequence 𝑣 subscript 𝐴 𝑝 𝐴 superscript 𝑣 subscript 𝐴 𝑞 𝐴 vA_{p}\subset A,\qquad v^{*}A_{q}\subset A. italic_v italic_A start_POSTSUBSCRIPT italic_p end_POSTSUBSCRIPT ⊂ italic_A , italic_v start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT italic_A start_POSTSUBSCRIPT italic_q end_POSTSUBSCRIPT ⊂ italic_A .

Definition 1 .

A function g : ρ F : 𝑔 𝜌 superscript 𝐹 g:\rho\rightarrow F^{\ast} italic_g : italic_ρ → italic_F start_POSTSUPERSCRIPT ∗ end_POSTSUPERSCRIPT is transitive if and only if

g ( i , j ) g ( j , k ) = g ( i , k ) 𝑔 𝑖 𝑗 𝑔 𝑗 𝑘 𝑔 𝑖 𝑘 g\left(i,j\right)g\left(j,k\right)=g\left(i,k\right) italic_g ( italic_i , italic_j ) italic_g ( italic_j , italic_k ) = italic_g ( italic_i , italic_k )

for all ( i , j ) , ( j , k ) ρ . 𝑖 𝑗 𝑗 𝑘 𝜌 \left(i,j\right),\left(j,k\right)\in\rho. ( italic_i , italic_j ) , ( italic_j , italic_k ) ∈ italic_ρ .


Definition 2.2 .

An affine permutation of order n 𝑛 n italic_n is a bijection f : normal-: 𝑓 normal-→ f:\mathbb{Z}\rightarrow\mathbb{Z} italic_f : blackboard_Z → blackboard_Z which satisfies the condition

(2.4) f ( i + n ) = f ( i ) + n 𝑓 𝑖 𝑛 𝑓 𝑖 𝑛 f(i+n)=f(i)+n italic_f ( italic_i + italic_n ) = italic_f ( italic_i ) + italic_n

for all i . 𝑖 i\in\mathbb{Z}. italic_i ∈ blackboard_Z . The affine permutations of order n 𝑛 n italic_n form a group, which we denote S ~ n . subscript normal-~ 𝑆 𝑛 \widetilde{S}_{n}. ~ start_ARG italic_S end_ARG start_POSTSUBSCRIPT italic_n end_POSTSUBSCRIPT .


DEFINITION 2.3 .

The subvariety 𝐃𝐌𝐒𝐇 𝟏 subscript 𝐃𝐌𝐒𝐇 1 \mathbf{DMSH_{1}} bold_DMSH start_POSTSUBSCRIPT bold_1 end_POSTSUBSCRIPT of level 1 of 𝐃𝐌𝐒𝐇 𝐃𝐌𝐒𝐇 \mathbf{DMSH} bold_DMSH is defined by the identity: x x * x 2 ( * ) x x * , fragments x superscript 𝑥 normal-′ superscript 𝑥 fragments 2 normal-( superscript fragments normal-′ normal-) x superscript 𝑥 normal-′ normal-, x\land x^{\prime*}\land x^{2{\rm(}}{{}^{\prime*{\rm{)}}}}\approx x\land x^{% \prime*}, italic_x ∧ italic_x start_POSTSUPERSCRIPT ′ * end_POSTSUPERSCRIPT ∧ italic_x start_POSTSUPERSCRIPT 2 ( end_POSTSUPERSCRIPT start_FLOATSUPERSCRIPT ′ * ) end_FLOATSUPERSCRIPT ≈ italic_x ∧ italic_x start_POSTSUPERSCRIPT ′ * end_POSTSUPERSCRIPT , or equivalently, by the identity:


Definition 3.1 .

A vector w 𝑤 w italic_w in a vector space V 𝑉 V italic_V (over {\mathbb{C}} blackboard_C ) on which a non-degenerate bi-linear form , fragments , \langle~{},~{}\rangle ⟨ , ⟩ is defined, is called isotropic with respect to that bi-linear form if

w , w = 0 . 𝑤 𝑤 0 \langle w,w\rangle=0. ⟨ italic_w , italic_w ⟩ = 0 .

(Note that the form is assumed to be bi-linear, not sesqui -linear.)


Definition 2.2 .

The point equivalence transformation of a class of PDEs ( 2.5 ) is an invertible transformation of the independent and dependent variables of the form

x ¯ = ϕ ( x , u ) , u ¯ = ψ ( x , u ) , formulae-sequence ¯ 𝑥 italic-ϕ 𝑥 𝑢 ¯ 𝑢 𝜓 𝑥 𝑢 missing-subexpression \begin{array}[]{ll}\bar{x}=\phi(x,u),\bar{u}=\psi(x,u),\\ \end{array} start_ARRAY start_ROW start_CELL ¯ start_ARG italic_x end_ARG = italic_ϕ ( italic_x , italic_u ) , ¯ start_ARG italic_u end_ARG = italic_ψ ( italic_x , italic_u ) , end_CELL start_CELL end_CELL end_ROW end_ARRAY (2.11)

that maps every equation of the class into an equation of the same family, viz.

E α ( x ¯ , u ¯ , , u ¯ ( k ) ) = 0 , α = 1 , , m . subscript 𝐸 𝛼 ¯ 𝑥 ¯ 𝑢 subscript ¯ 𝑢 𝑘 0 𝛼 1 𝑚 \begin{array}[]{ll}E_{\alpha}(\bar{x},\bar{u},...,\bar{u}_{(k)})=0,&\alpha=1,.% ..,m.\end{array} start_ARRAY start_ROW start_CELL italic_E start_POSTSUBSCRIPT italic_α end_POSTSUBSCRIPT ( ¯ start_ARG italic_x end_ARG , ¯ start_ARG italic_u end_ARG , … , ¯ start_ARG italic_u end_ARG start_POSTSUBSCRIPT ( italic_k ) end_POSTSUBSCRIPT ) = 0 , end_CELL start_CELL italic_α = 1 , … , italic_m . end_CELL end_ROW end_ARRAY (2.12)

Definition \thechapter .3 .

An assignment s 𝑠 s italic_s on 𝔐 𝔐 \mathfrak{M} fraktur_M is a function s : Var | 𝔐 | : 𝑠 Var 𝔐 s\colon\mathrm{Var}\to\left|\mathfrak{M}\right| italic_s : roman_Var → | fraktur_M | .

If x Var 𝑥 Var x\in\mathrm{Var} italic_x ∈ roman_Var and m | 𝔐 | 𝑚 𝔐 m\in\left|\mathfrak{M}\right| italic_m ∈ | fraktur_M | , s [ x / m ] 𝑠 delimited-[] 𝑥 𝑚 s[x/m] italic_s [ italic_x / italic_m ] is the assignment defined by

s [ x / m ] ( y ) = { m if y = x s ( y ) otherwise 𝑠 delimited-[] 𝑥 𝑚 𝑦 cases 𝑚 if y = x 𝑠 𝑦 otherwise s[x/m](y)=\begin{cases}m&\text{if $y=x$}\\ s(y)&\text{otherwise}\end{cases} italic_s [ italic_x / italic_m ] ( italic_y ) = { start_ROW start_CELL italic_m end_CELL start_CELL if italic_y = italic_x end_CELL end_ROW start_ROW start_CELL italic_s ( italic_y ) end_CELL start_CELL otherwise end_CELL end_ROW

Definition 2.2 ( [ 13 ] ) .

Let ( A , μ , α ) 𝐴 𝜇 𝛼 (A,\mu,\alpha) ( italic_A , italic_μ , italic_α ) and ( A , μ , α ) superscript 𝐴 normal-′ superscript 𝜇 normal-′ superscript 𝛼 normal-′ (A^{\prime},\mu^{\prime},\alpha^{\prime}) ( italic_A start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_μ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_α start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) be two Hom-alternative algebras. A linear map f : A A normal-: 𝑓 normal-→ 𝐴 superscript 𝐴 normal-′ f:A\to A^{\prime} italic_f : italic_A → italic_A start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT is said to be a morphism of Hom-alternative algebras if

μ ( f f ) = f μ and f α = α f . superscript 𝜇 tensor-product 𝑓 𝑓 𝑓 𝜇 and 𝑓 𝛼 superscript 𝛼 𝑓 \mu^{\prime}\circ(f\otimes f)=f\circ\mu\text{ and }f\circ\alpha=\alpha^{\prime% }\circ f. italic_μ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ∘ ( italic_f ⊗ italic_f ) = italic_f ∘ italic_μ and italic_f ∘ italic_α = italic_α start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ∘ italic_f . (3)

Definition 2.2 .

A locally defined p 𝑝 p italic_p -form λ 𝜆 \lambda italic_λ of J k ( E ) superscript 𝐽 𝑘 𝐸 J^{k}(E) italic_J start_POSTSUPERSCRIPT italic_k end_POSTSUPERSCRIPT ( italic_E ) , p 1 𝑝 1 p\geq 1 italic_p ≥ 1 , is called holonomic if ı X λ = 0 subscript italic-ı 𝑋 𝜆 0 \imath_{X}\lambda=0 italic_ı start_POSTSUBSCRIPT italic_X end_POSTSUBSCRIPT italic_λ = 0 for any holonomic vector field X 𝑋 X italic_X . A local 0 0 -form (i.e., a 𝒞 superscript 𝒞 \mathcal{C}^{\infty} caligraphic_C start_POSTSUPERSCRIPT ∞ end_POSTSUPERSCRIPT function on an open set) is called holonomic if it vanishes identically.

If α 𝛼 \alpha italic_α , α superscript 𝛼 \alpha^{\prime} italic_α start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT are p 𝑝 p italic_p -forms on the same open subset 𝒰 J k ( E ) 𝒰 superscript 𝐽 𝑘 𝐸 \mathcal{U}\subset J^{k}(E) caligraphic_U ⊂ italic_J start_POSTSUPERSCRIPT italic_k end_POSTSUPERSCRIPT ( italic_E ) , they are called variationally equivalent if

α - α = λ + d μ 𝛼 superscript 𝛼 𝜆 𝑑 𝜇 \alpha-\alpha^{\prime}=\lambda+d\mu italic_α - italic_α start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT = italic_λ + italic_d italic_μ

for some holonomic p 𝑝 p italic_p -form λ 𝜆 \lambda italic_λ and some holonomic ( p - 1 ) 𝑝 1 (p-1) ( italic_p - 1 ) -form μ 𝜇 \mu italic_μ .


Definition 4.8 .

Suppose that D , D ~ 𝐷 ~ 𝐷 D,\widetilde{D} italic_D , ~ start_ARG italic_D end_ARG are closed subsets of \mathbb{C} blackboard_C . A degree 1 1 1 1 map (in z 𝑧 z italic_z and z ¯ ¯ 𝑧 \bar{z} ¯ start_ARG italic_z end_ARG separately) on D 𝐷 D italic_D is a function f 𝑓 f italic_f from D 𝐷 D italic_D to \mathbb{C} blackboard_C of the form

(1) f ( z ) = α + β z + γ z ¯ + δ z z ¯ 𝑓 𝑧 𝛼 𝛽 𝑧 𝛾 ¯ 𝑧 𝛿 𝑧 ¯ 𝑧 f(z)=\alpha+\beta z+\gamma\bar{z}+\delta z\bar{z}\text{} italic_f ( italic_z ) = italic_α + italic_β italic_z + italic_γ ¯ start_ARG italic_z end_ARG + italic_δ italic_z ¯ start_ARG italic_z end_ARG

for some α , β , γ , δ 𝛼 𝛽 𝛾 𝛿 \alpha,\beta,\gamma,\delta\in\mathbb{C} italic_α , italic_β , italic_γ , italic_δ ∈ blackboard_C such that moreover for some α , β , γ , δ superscript 𝛼 superscript 𝛽 superscript 𝛾 superscript 𝛿 \alpha^{\prime},\beta^{\prime},\gamma^{\prime},\delta^{\prime}\in\mathbb{C} italic_α start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_β start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_γ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_δ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ∈ blackboard_C ,

(2) f ( z ) f ( z ) ¯ = α + β z + γ z + δ z z ¯ 𝑓 𝑧 ¯ 𝑓 𝑧 superscript 𝛼 superscript 𝛽 𝑧 superscript 𝛾 𝑧 superscript 𝛿 𝑧 ¯ 𝑧 f(z)\overline{f(z)}=\alpha^{\prime}+\beta^{\prime}z+\gamma^{\prime}z+\delta^{% \prime}z\bar{z}\text{} italic_f ( italic_z ) ¯ start_ARG italic_f ( italic_z ) end_ARG = italic_α start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT + italic_β start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT italic_z + italic_γ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT italic_z + italic_δ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT italic_z ¯ start_ARG italic_z end_ARG

for every z D 𝑧 𝐷 z\in D italic_z ∈ italic_D . A degree 1 1 1 1 homeomorphism from D 𝐷 D italic_D to D ~ ~ 𝐷 \widetilde{D} ~ start_ARG italic_D end_ARG is a homeomorphism φ : D D ~ : 𝜑 𝐷 ~ 𝐷 \varphi:D\rightarrow\widetilde{D} italic_φ : italic_D → ~ start_ARG italic_D end_ARG such that φ 𝜑 \varphi italic_φ and φ - 1 superscript 𝜑 1 \varphi^{-1} italic_φ start_POSTSUPERSCRIPT - 1 end_POSTSUPERSCRIPT are degree 1 1 1 1 maps. The closed subsets D 𝐷 D italic_D and D ~ ~ 𝐷 \widetilde{D} ~ start_ARG italic_D end_ARG of \mathbb{C} blackboard_C are degree 1 1 1 1 homeomorphic if there is a degree 1 1 1 1 homeomorphism from D 𝐷 D italic_D to D ~ ~ 𝐷 \widetilde{D} ~ start_ARG italic_D end_ARG .


Definition 2.1 .

[ 11 ] A right Leibniz algebra L 𝐿 L italic_L is a vector space over a field 𝕂 𝕂 \mathbb{K} blackboard_K endowed with a bilinear product [ , ] normal-⋅ normal-⋅ [\cdot,\cdot] [ ⋅ , ⋅ ] satisfying the Leibniz identity

[ [ y , z ] , x ] = [ [ y , x ] , z ] + [ y , [ z , x ] ] , 𝑦 𝑧 𝑥 𝑦 𝑥 𝑧 𝑦 𝑧 𝑥 [[y,z],x]=[[y,x],z]+[y,[z,x]], [ [ italic_y , italic_z ] , italic_x ] = [ [ italic_y , italic_x ] , italic_z ] + [ italic_y , [ italic_z , italic_x ] ] ,

for all x , y , z L 𝑥 𝑦 𝑧 𝐿 x,y,z\in L italic_x , italic_y , italic_z ∈ italic_L .

Definition 2.2 .

[ 7 ] A Leibniz triple system is a vector space T 𝑇 T italic_T endowed with a trilinear operation { , , } : T × T × T T normal-: normal-⋅ normal-⋅ normal-⋅ normal-→ 𝑇 𝑇 𝑇 𝑇 \{\cdot,\cdot,\cdot\}:T\times T\times T\rightarrow T { ⋅ , ⋅ , ⋅ } : italic_T × italic_T × italic_T → italic_T satisfying

{ a , { b , c , d } , e } = { { a , b , c } , d , e } - { { a , c , b } , d , e } - { { a , d , b } , c , e } + { { a , d , c } , b , e } , fragments { a , fragments { b , c , d } , e } { fragments { a , b , c } , d , e } { fragments { a , c , b } , d , e } { fragments { a , d , b } , c , e } { fragments { a , d , c } , b , e } , \displaystyle\{a,\{b,c,d\},e\}\!=\!\{\{a,b,c\},d,e\}\!-\!\{\{a,c,b\},d,e\}\!-% \!\{\{a,d,b\},c,e\}\!+\!\{\{a,d,c\},b,e\}, { italic_a , { italic_b , italic_c , italic_d } , italic_e } = { { italic_a , italic_b , italic_c } , italic_d , italic_e } - { { italic_a , italic_c , italic_b } , italic_d , italic_e } - { { italic_a , italic_d , italic_b } , italic_c , italic_e } + { { italic_a , italic_d , italic_c } , italic_b , italic_e } , (2.1)
{ a , b , { c , d , e } } = { { a , b , c } , d , e } - { { a , b , d } , c , e } - { { a , b , e } , c , d } + { { a , b , e } , d , c } , fragments { a , b , fragments { c , d , e } } { fragments { a , b , c } , d , e } { fragments { a , b , d } , c , e } { fragments { a , b , e } , c , d } { fragments { a , b , e } , d , c } , \displaystyle\{a,b,\{c,d,e\}\}\!=\!\{\{a,b,c\},d,e\}\!-\!\{\{a,b,d\},c,e\}\!-% \!\{\{a,b,e\},c,d\}\!+\!\{\{a,b,e\},d,c\}, { italic_a , italic_b , { italic_c , italic_d , italic_e } } = { { italic_a , italic_b , italic_c } , italic_d , italic_e } - { { italic_a , italic_b , italic_d } , italic_c , italic_e } - { { italic_a , italic_b , italic_e } , italic_c , italic_d } + { { italic_a , italic_b , italic_e } , italic_d , italic_c } , (2.2)

for all a , b , c , d , e T 𝑎 𝑏 𝑐 𝑑 𝑒 𝑇 a,b,c,d,e\in T italic_a , italic_b , italic_c , italic_d , italic_e ∈ italic_T .


Definition 2.2 (Metropolis-Hastings kernel) .

Given the current state u k subscript 𝑢 𝑘 u_{k} italic_u start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT , a candidate state u superscript 𝑢 normal-′ u^{\prime} italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT is drawn from the proposal distribution q ( u k , ) 𝑞 subscript 𝑢 𝑘 normal-⋅ q(u_{k},\cdot) italic_q ( italic_u start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT , ⋅ ) . Define the pair of measures

ν ( d u , d u ) = q ( u , d u ) μ ( d u ) ν ( d u , d u ) = q ( u , d u ) μ ( d u ) . 𝜈 𝑑 𝑢 𝑑 superscript 𝑢 𝑞 𝑢 𝑑 superscript 𝑢 𝜇 𝑑 𝑢 superscript 𝜈 bottom 𝑑 𝑢 𝑑 superscript 𝑢 𝑞 superscript 𝑢 𝑑 𝑢 𝜇 𝑑 superscript 𝑢 \begin{array}[]{rll}\nu(du,du^{\prime})&=&q(u,du^{\prime})\mu(du)\\ \nu^{\bot}(du,du^{\prime})&=&q(u^{\prime},du)\mu(du^{\prime}).\end{array} start_ARRAY start_ROW start_CELL italic_ν ( italic_d italic_u , italic_d italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) end_CELL start_CELL = end_CELL start_CELL italic_q ( italic_u , italic_d italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) italic_μ ( italic_d italic_u ) end_CELL end_ROW start_ROW start_CELL italic_ν start_POSTSUPERSCRIPT ⊥ end_POSTSUPERSCRIPT ( italic_d italic_u , italic_d italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) end_CELL start_CELL = end_CELL start_CELL italic_q ( italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_d italic_u ) italic_μ ( italic_d italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) . end_CELL end_ROW end_ARRAY (5)

Then the next state of the Markov chain is set to u k + 1 = u subscript 𝑢 𝑘 1 superscript 𝑢 normal-′ u_{k+1}=u^{\prime} italic_u start_POSTSUBSCRIPT italic_k + 1 end_POSTSUBSCRIPT = italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT with probability

α ( u k , u ) = min { 1 , d ν d ν ( u k , u ) } ; 𝛼 subscript 𝑢 𝑘 superscript 𝑢 min 1 𝑑 superscript 𝜈 bottom 𝑑 𝜈 subscript 𝑢 𝑘 superscript 𝑢 \alpha(u_{k},u^{\prime})={\rm min}\left\{1,\frac{d\nu^{\bot}}{d\nu}(u_{k},u^{% \prime})\right\}; italic_α ( italic_u start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT , italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) = roman_min { 1 , divide start_ARG italic_d italic_ν start_POSTSUPERSCRIPT ⊥ end_POSTSUPERSCRIPT end_ARG start_ARG italic_d italic_ν end_ARG ( italic_u start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT , italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) } ; (6)

otherwise, with probability 1 - α ( u k , u ) 1 𝛼 subscript 𝑢 𝑘 superscript 𝑢 normal-′ 1-\alpha(u_{k},u^{\prime}) 1 - italic_α ( italic_u start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT , italic_u start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) , it is set to u k + 1 = u k subscript 𝑢 𝑘 1 subscript 𝑢 𝑘 u_{k+1}=u_{k} italic_u start_POSTSUBSCRIPT italic_k + 1 end_POSTSUBSCRIPT = italic_u start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT .


Definition 2.2 .

[ 4 ] A map ϕ : G × G × G 𝕂 × : italic-ϕ 𝐺 𝐺 𝐺 superscript 𝕂 \phi:G\times G\times G\longrightarrow\mathbb{K}^{\times} italic_ϕ : italic_G × italic_G × italic_G ⟶ blackboard_K start_POSTSUPERSCRIPT × end_POSTSUPERSCRIPT is called a cocycle if

ϕ ( h , k , l ) ϕ ( g , h k , l ) ϕ ( g , h , k ) = ϕ ( g , h , k l ) ϕ ( g h , k , l ) , italic-ϕ 𝑘 𝑙 italic-ϕ 𝑔 𝑘 𝑙 italic-ϕ 𝑔 𝑘 italic-ϕ 𝑔 𝑘 𝑙 italic-ϕ 𝑔 𝑘 𝑙 \displaystyle\phi(h,k,l)\phi(g,hk,l)\phi(g,h,k)=\phi(g,h,kl)\phi(gh,k,l), italic_ϕ ( italic_h , italic_k , italic_l ) italic_ϕ ( italic_g , italic_h italic_k , italic_l ) italic_ϕ ( italic_g , italic_h , italic_k ) = italic_ϕ ( italic_g , italic_h , italic_k italic_l ) italic_ϕ ( italic_g italic_h , italic_k , italic_l ) , (2.1)
ϕ ( g , e , h ) = 1 , italic-ϕ 𝑔 𝑒 1 \displaystyle\phi(g,e,h)=1, italic_ϕ ( italic_g , italic_e , italic_h ) = 1 , (2.2)

hold for any g , h , k , l G 𝑔 𝑘 𝑙 𝐺 g,h,k,l\in G italic_g , italic_h , italic_k , italic_l ∈ italic_G , where e 𝑒 e italic_e is the identity of G 𝐺 G italic_G .

Definition 5.5 .

Take an automorphism system σ : G A u t ( 𝕂 ) : 𝜎 𝐺 𝐴 𝑢 𝑡 𝕂 \sigma:G\rightarrow Aut(\mathbb{K}) italic_σ : italic_G → italic_A italic_u italic_t ( blackboard_K ) , where we consider the field 𝕂 𝕂 \mathbb{K} blackboard_K as the associative algebra B 𝐵 B italic_B on the natural way. A quasicrossed mapping δ : G × G 𝕂 × : 𝛿 𝐺 𝐺 superscript 𝕂 \delta:G\times G\rightarrow\mathbb{K}^{\times} italic_δ : italic_G × italic_G → blackboard_K start_POSTSUPERSCRIPT × end_POSTSUPERSCRIPT (see Definition 4.7 ) is called a coboundary if there is a function u : G 𝕂 × : 𝑢 𝐺 superscript 𝕂 u:G\rightarrow\mathbb{K}^{\times} italic_u : italic_G → blackboard_K start_POSTSUPERSCRIPT × end_POSTSUPERSCRIPT such that

δ ( g , h ) = u ( g ) σ ( g ) ( u ( h ) ) u ( g h ) - 1 , 𝛿 𝑔 𝑢 𝑔 𝜎 𝑔 𝑢 𝑢 superscript 𝑔 1 \begin{split}\displaystyle\delta(g,h)=u(g)\sigma(g)(u(h))u(gh)^{-1},\end{split} start_ROW start_CELL italic_δ ( italic_g , italic_h ) = italic_u ( italic_g ) italic_σ ( italic_g ) ( italic_u ( italic_h ) ) italic_u ( italic_g italic_h ) start_POSTSUPERSCRIPT - 1 end_POSTSUPERSCRIPT , end_CELL end_ROW

for any g , h G 𝑔 𝐺 g,h\in G italic_g , italic_h ∈ italic_G .


Definition .

We say that there exists a quantum homomorphism from a graph X 𝑋 X italic_X to a graph Y 𝑌 Y italic_Y , and write X 𝑞 Y 𝑞 𝑋 𝑌 X\xrightarrow{q}Y italic_X start_ARROW italic_q → end_ARROW italic_Y , if there exist positive semidefinite matrices ρ x y subscript 𝜌 𝑥 𝑦 \rho_{xy} italic_ρ start_POSTSUBSCRIPT italic_x italic_y end_POSTSUBSCRIPT for x V ( X ) , y V ( Y ) formulae-sequence 𝑥 𝑉 𝑋 𝑦 𝑉 𝑌 x\in V(X),y\in V(Y) italic_x ∈ italic_V ( italic_X ) , italic_y ∈ italic_V ( italic_Y ) and ρ 𝜌 \rho italic_ρ satisfying

ρ , ρ = 1 𝜌 𝜌 1 \displaystyle\langle\rho,\rho\rangle=1 ⟨ italic_ρ , italic_ρ ⟩ = 1
y V ( Y ) ρ x y = ρ for all x V ( X ) subscript 𝑦 𝑉 𝑌 subscript 𝜌 𝑥 𝑦 𝜌 for all 𝑥 𝑉 𝑋 \displaystyle\sum_{y\in V(Y)}\rho_{xy}=\rho\text{ for all }x\in V(X) ∑ start_POSTSUBSCRIPT italic_y ∈ italic_V ( italic_Y ) end_POSTSUBSCRIPT italic_ρ start_POSTSUBSCRIPT italic_x italic_y end_POSTSUBSCRIPT = italic_ρ for all italic_x ∈ italic_V ( italic_X )
ρ x y , ρ x y = 0 if ( x = x & y y ) or ( x x & y ≁ y ) fragments fragments subscript 𝜌 𝑥 𝑦 , subscript 𝜌 superscript 𝑥 superscript 𝑦 0 if fragments ( x superscript 𝑥 y superscript 𝑦 ) or fragments ( x similar-to superscript 𝑥 y not-similar-to superscript 𝑦 ) \displaystyle\langle\rho_{xy},\rho_{x^{\prime}y^{\prime}}\rangle=0\text{ if }(% x=x^{\prime}\ \&\ y\neq y^{\prime})\text{ or }(x\sim x^{\prime}\ \&\ y\not\sim y% ^{\prime}) ⟨ italic_ρ start_POSTSUBSCRIPT italic_x italic_y end_POSTSUBSCRIPT , italic_ρ start_POSTSUBSCRIPT italic_x start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT italic_y start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT end_POSTSUBSCRIPT ⟩ = 0 if ( italic_x = italic_x start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT & italic_y ≠ italic_y start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) or ( italic_x ∼ italic_x start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT & italic_y ≁ italic_y start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT )
Definition .

We say that there exists a entanglement-assisted homomorphism from a graph X 𝑋 X italic_X to a graph Y 𝑌 Y italic_Y , and write X * Y 𝑋 𝑌 X\xrightarrow{*}Y italic_X start_ARROW * → end_ARROW italic_Y , if there exist positive semidefinite matrices ρ x y subscript 𝜌 𝑥 𝑦 \rho_{xy} italic_ρ start_POSTSUBSCRIPT italic_x italic_y end_POSTSUBSCRIPT for x V ( X ) , y V ( Y ) formulae-sequence 𝑥 𝑉 𝑋 𝑦 𝑉 𝑌 x\in V(X),y\in V(Y) italic_x ∈ italic_V ( italic_X ) , italic_y ∈ italic_V ( italic_Y ) and ρ 𝜌 \rho italic_ρ satisfying

ρ , ρ = 1 𝜌 𝜌 1 \displaystyle\langle\rho,\rho\rangle=1 ⟨ italic_ρ , italic_ρ ⟩ = 1
y V ( Y ) ρ x y = ρ for all x V ( X ) subscript 𝑦 𝑉 𝑌 subscript 𝜌 𝑥 𝑦 𝜌 for all 𝑥 𝑉 𝑋 \displaystyle\sum_{y\in V(Y)}\rho_{xy}=\rho\text{ for all }x\in V(X) ∑ start_POSTSUBSCRIPT italic_y ∈ italic_V ( italic_Y ) end_POSTSUBSCRIPT italic_ρ start_POSTSUBSCRIPT italic_x italic_y end_POSTSUBSCRIPT = italic_ρ for all italic_x ∈ italic_V ( italic_X )
ρ x y , ρ x y = 0 if ( x x & y ≁ y ) fragments fragments subscript 𝜌 𝑥 𝑦 , subscript 𝜌 superscript 𝑥 superscript 𝑦 0 if fragments ( x similar-to superscript 𝑥 y not-similar-to superscript 𝑦 ) \displaystyle\langle\rho_{xy},\rho_{x^{\prime}y^{\prime}}\rangle=0\text{ if }(% x\sim x^{\prime}\ \&\ y\not\sim y^{\prime}) ⟨ italic_ρ start_POSTSUBSCRIPT italic_x italic_y end_POSTSUBSCRIPT , italic_ρ start_POSTSUBSCRIPT italic_x start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT italic_y start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT end_POSTSUBSCRIPT ⟩ = 0 if ( italic_x ∼ italic_x start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT & italic_y ≁ italic_y start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT )

Definition 3.1 .

Define

𝐪 ( t ) = [ 𝐲 ( t ) 𝐳 ( t ) ] 𝐪 𝑡 delimited-[] 𝐲 𝑡 𝐳 𝑡 {\bf q}(t)=\left[\begin{array}[]{c}{\bf y}(t)\\ {\bf z}(t)\end{array}\right] bold_q ( italic_t ) = [ start_ARRAY start_ROW start_CELL bold_y ( italic_t ) end_CELL end_ROW start_ROW start_CELL bold_z ( italic_t ) end_CELL end_ROW end_ARRAY ]

We will use the notation B 𝐵 B italic_B to denote the matrix

B = [ α M - ( α - 1 ) M I 0 ] 𝐵 delimited-[] 𝛼 superscript 𝑀 𝛼 1 superscript 𝑀 𝐼 0 B=\left[\begin{array}[]{cc}\alpha M^{\prime}&-(\alpha-1)M^{\prime}\\ I&0\end{array}\right] italic_B = [ start_ARRAY start_ROW start_CELL italic_α italic_M start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT end_CELL start_CELL - ( italic_α - 1 ) italic_M start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT end_CELL end_ROW start_ROW start_CELL italic_I end_CELL start_CELL 0 end_CELL end_ROW end_ARRAY ]

where α = 2 - 2 / ( 9 U + 1 ) 𝛼 2 2 9 𝑈 1 \alpha=2-2/(9U+1) italic_α = 2 - 2 / ( 9 italic_U + 1 ) ; note that in the previous section this would have been denoted B ( 1 ) 𝐵 1 B(1) italic_B ( 1 ) . Finally, we will use 𝐠 ( t ) 𝐠 𝑡 {\bf g}(t) bold_g ( italic_t ) to denote the vector that stacks up the subgradients g i ( t ) , i = 1 , , n formulae-sequence subscript 𝑔 𝑖 𝑡 𝑖 1 normal-… 𝑛 g_{i}(t),i=1,\ldots,n italic_g start_POSTSUBSCRIPT italic_i end_POSTSUBSCRIPT ( italic_t ) , italic_i = 1 , … , italic_n .


Definition 311 .

(Multiplier semigroup) Let ( S , * ) 𝑆 (S,*) ( italic_S , * ) be an involutive semigroup. A multiplier of S 𝑆 S italic_S is a pair ( λ , ρ ) 𝜆 𝜌 (\lambda,\rho) ( italic_λ , italic_ρ ) of mappings λ , ρ : S S : 𝜆 𝜌 𝑆 𝑆 \lambda,\rho\colon S\to S italic_λ , italic_ρ : italic_S → italic_S satisfying the following conditions:

The map λ 𝜆 \lambda italic_λ is called the left action of the multiplier and ρ 𝜌 \rho italic_ρ is called the right action of the multiplier. For m = ( λ , ρ ) 𝑚 𝜆 𝜌 m=(\lambda,\rho) italic_m = ( italic_λ , italic_ρ ) and s S 𝑠 𝑆 s\in S italic_s ∈ italic_S we write

m s := λ ( s ) and s m := ρ ( s ) . formulae-sequence assign 𝑚 𝑠 𝜆 𝑠 and assign 𝑠 𝑚 𝜌 𝑠 ms:=\lambda(s)\quad\mbox{ and }\quad sm:=\rho(s). italic_m italic_s := italic_λ ( italic_s ) and italic_s italic_m := italic_ρ ( italic_s ) .

We write M ( S ) 𝑀 𝑆 M(S) italic_M ( italic_S ) for the set of all multipliers of S 𝑆 S italic_S and turn it into an involutive semigroup by

( λ , ρ ) ( λ , ρ ) := ( λ λ , ρ ρ ) and ( λ , ρ ) * := ( ρ * , λ * ) formulae-sequence assign 𝜆 𝜌 superscript 𝜆 superscript 𝜌 𝜆 superscript 𝜆 superscript 𝜌 𝜌 and assign superscript 𝜆 𝜌 superscript 𝜌 superscript 𝜆 (\lambda,\rho)(\lambda^{\prime},\rho^{\prime}):=(\lambda\circ\lambda^{\prime},% \rho^{\prime}\circ\rho)\quad\mbox{ and }\quad(\lambda,\rho)^{*}:=(\rho^{*},% \lambda^{*}) ( italic_λ , italic_ρ ) ( italic_λ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_ρ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ) := ( italic_λ ∘ italic_λ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_ρ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ∘ italic_ρ ) and ( italic_λ , italic_ρ ) start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT := ( italic_ρ start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT , italic_λ start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT )

with λ * ( a ) := λ ( a * ) * assign superscript 𝜆 𝑎 𝜆 superscript superscript 𝑎 \lambda^{*}(a):=\lambda(a^{*})^{*} italic_λ start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT ( italic_a ) := italic_λ ( italic_a start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT ) start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT and ρ * ( a ) = ρ ( a * ) * superscript 𝜌 𝑎 𝜌 superscript superscript 𝑎 \rho^{*}(a)=\rho(a^{*})^{*} italic_ρ start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT ( italic_a ) = italic_ρ ( italic_a start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT ) start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT (see [ Jo64 ] ).


Definition 3.3 .

Let k = 2 m + 1 𝑘 2 𝑚 1 k=2m+1 italic_k = 2 italic_m + 1 and l = 2 n + 1 𝑙 2 𝑛 1 l=2n+1 italic_l = 2 italic_n + 1 . For ρ : π 1 ( k , l ) SL 2 ( ) normal-: 𝜌 normal-→ subscript 𝜋 1 𝑘 𝑙 subscript normal-SL 2 \rho:\pi_{1}(k,l)\rightarrow\mathrm{SL}_{2}(\mathbb{C}) italic_ρ : italic_π start_POSTSUBSCRIPT 1 end_POSTSUBSCRIPT ( italic_k , italic_l ) → roman_SL start_POSTSUBSCRIPT 2 end_POSTSUBSCRIPT ( blackboard_C ) define

x = tr ρ ( a ) , y = tr ρ ( b ) 𝑎𝑛𝑑 z = tr ρ ( a b - 1 ) formulae-sequence 𝑥 tr 𝜌 𝑎 𝑦 tr 𝜌 𝑏 𝑎𝑛𝑑 𝑧 tr 𝜌 𝑎 superscript 𝑏 1 x=\operatorname{\mathrm{t}r}\rho(a),~{}y=\operatorname{\mathrm{t}r}\rho(b)\ % \text{and}\ z=\operatorname{\mathrm{t}r}\rho(ab^{-1}) italic_x = roman_tr italic_ρ ( italic_a ) , italic_y = roman_tr italic_ρ ( italic_b ) and italic_z = roman_tr italic_ρ ( italic_a italic_b start_POSTSUPERSCRIPT - 1 end_POSTSUPERSCRIPT )

and for a word u 𝑢 u italic_u in F a , b subscript 𝐹 𝑎 𝑏 F_{a,b} italic_F start_POSTSUBSCRIPT italic_a , italic_b end_POSTSUBSCRIPT define the polynomial P u ( x , y , z ) = tr ρ ( u ) [ x , y , z ] subscript 𝑃 𝑢 𝑥 𝑦 𝑧 normal-tr 𝜌 𝑢 𝑥 𝑦 𝑧 P_{u}(x,y,z)=\operatorname{\mathrm{t}r}\rho(u)\in\mathbb{C}[x,y,z] italic_P start_POSTSUBSCRIPT italic_u end_POSTSUBSCRIPT ( italic_x , italic_y , italic_z ) = roman_tr italic_ρ ( italic_u ) ∈ blackboard_C [ italic_x , italic_y , italic_z ] . Further, let t = P w k 𝑡 subscript 𝑃 subscript 𝑤 𝑘 t=P_{w_{k}} italic_t = italic_P start_POSTSUBSCRIPT italic_w start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT end_POSTSUBSCRIPT and

φ ( x , y , z ) = P r a b - P r a b . 𝜑 𝑥 𝑦 𝑧 subscript 𝑃 𝑟 𝑎 𝑏 subscript 𝑃 𝑟 𝑎 𝑏 \varphi(x,y,z)=P_{rab}-P_{\overleftarrow{r}ab}. italic_φ ( italic_x , italic_y , italic_z ) = italic_P start_POSTSUBSCRIPT italic_r italic_a italic_b end_POSTSUBSCRIPT - italic_P start_POSTSUBSCRIPT ← start_ARG italic_r end_ARG italic_a italic_b end_POSTSUBSCRIPT .

Definition 5.1 .

A map μ : 𝒫 ( ) [ 0 , ] normal-: 𝜇 normal-→ 𝒫 0 \mu:\mathcal{P}(\mathbb{N})\rightarrow[0,\infty] italic_μ : caligraphic_P ( blackboard_N ) → [ 0 , ∞ ] is a submeasure supported by \mathbb{N} blackboard_N if for A , B 𝐴 𝐵 A,B\subseteq\mathbb{N} italic_A , italic_B ⊆ blackboard_N

μ ( ) = 0 𝜇 0 \displaystyle\mu(\emptyset)=0 italic_μ ( ∅ ) = 0
μ ( A ) μ ( A B ) μ ( A ) + μ ( B ) . 𝜇 𝐴 𝜇 𝐴 𝐵 𝜇 𝐴 𝜇 𝐵 \displaystyle\mu(A)\leq\mu(A\cup B)\leq\mu(A)+\mu(B). italic_μ ( italic_A ) ≤ italic_μ ( italic_A ∪ italic_B ) ≤ italic_μ ( italic_A ) + italic_μ ( italic_B ) .

It is lower semicontinuous if for all A 𝐴 A\subseteq\mathbb{N} italic_A ⊆ blackboard_N we have

μ ( A ) = lim n μ ( A [ 1 , n ] ) . 𝜇 𝐴 subscript 𝑛 𝜇 𝐴 1 𝑛 \mu(A)=\lim_{n\rightarrow\infty}\mu(A\cap[1,n]). italic_μ ( italic_A ) = roman_lim start_POSTSUBSCRIPT italic_n → ∞ end_POSTSUBSCRIPT italic_μ ( italic_A ∩ [ 1 , italic_n ] ) .

Definition 1 .

A dressing field is a map u ¯ : 𝒫 H : ¯ 𝑢 𝒫 𝐻 {\bar{u}}:\mathcal{P}\rightarrow H ¯ start_ARG italic_u end_ARG : caligraphic_P → italic_H with equivariance property h * u ¯ = h - 1 u ¯ subscript superscript ¯ 𝑢 superscript 1 ¯ 𝑢 \mathcal{R}^{*}_{h}{\bar{u}}=h^{-1}{\bar{u}} caligraphic_R start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT start_POSTSUBSCRIPT italic_h end_POSTSUBSCRIPT ¯ start_ARG italic_u end_ARG = italic_h start_POSTSUPERSCRIPT - 1 end_POSTSUPERSCRIPT ¯ start_ARG italic_u end_ARG and on which the action of the gauge group \mathcal{H} caligraphic_H is thus

u ¯ γ ¯ = γ ¯ - 1 u ¯ . superscript ¯ 𝑢 ¯ 𝛾 superscript ¯ 𝛾 1 ¯ 𝑢 \displaystyle{\bar{u}}^{\bar{\gamma}}={\bar{\gamma}}^{-1}{\bar{u}}. ¯ start_ARG italic_u end_ARG start_POSTSUPERSCRIPT ¯ start_ARG italic_γ end_ARG end_POSTSUPERSCRIPT = ¯ start_ARG italic_γ end_ARG start_POSTSUPERSCRIPT - 1 end_POSTSUPERSCRIPT ¯ start_ARG italic_u end_ARG . (4)

Definition 11 .

An automorphism of a * * * -algebra 𝒜 𝒜 \mathcal{A} caligraphic_A is a linear invertible map α : 𝒜 𝒜 normal-: 𝛼 normal-→ 𝒜 𝒜 \alpha:\mathcal{A}\to\mathcal{A} italic_α : caligraphic_A → caligraphic_A that satisfies

α ( a b ) = α ( a ) α ( b ) , α ( a * ) = α ( a ) * . formulae-sequence 𝛼 𝑎 𝑏 𝛼 𝑎 𝛼 𝑏 𝛼 superscript 𝑎 𝛼 superscript 𝑎 \alpha(ab)=\alpha(a)\alpha(b),\qquad\alpha(a^{*})=\alpha(a)^{*}. italic_α ( italic_a italic_b ) = italic_α ( italic_a ) italic_α ( italic_b ) , italic_α ( italic_a start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT ) = italic_α ( italic_a ) start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT .

We denote the group of automorphisms of the * * * -algebra 𝒜 𝒜 \mathcal{A} caligraphic_A by Aut ( 𝒜 ) normal-Aut 𝒜 \operatorname{Aut}(\mathcal{A}) roman_Aut ( caligraphic_A ) .

An automorphism α 𝛼 \alpha italic_α is called inner if it is of the form α ( a ) = u a u * 𝛼 𝑎 𝑢 𝑎 superscript 𝑢 \alpha(a)=uau^{*} italic_α ( italic_a ) = italic_u italic_a italic_u start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT for some element u 𝒰 ( 𝒜 ) 𝑢 𝒰 𝒜 u\in\mathcal{U}(\mathcal{A}) italic_u ∈ caligraphic_U ( caligraphic_A ) where

𝒰 ( 𝒜 ) = { u 𝒜 : u u * = u * u = 1 } 𝒰 𝒜 conditional-set 𝑢 𝒜 𝑢 superscript 𝑢 superscript 𝑢 𝑢 1 \mathcal{U}(\mathcal{A})=\{u\in\mathcal{A}:uu^{*}=u^{*}u=1\} caligraphic_U ( caligraphic_A ) = { italic_u ∈ caligraphic_A : italic_u italic_u start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT = italic_u start_POSTSUPERSCRIPT * end_POSTSUPERSCRIPT italic_u = 1 }

is the group of unitary elements in 𝒜 𝒜 \mathcal{A} caligraphic_A . The group of inner automorphisms is denoted by Inn ( 𝒜 ) normal-Inn 𝒜 \operatorname{Inn}(\mathcal{A}) roman_Inn ( caligraphic_A ) .

The group of outer automorphisms of 𝒜 𝒜 \mathcal{A} caligraphic_A is defined by the quotient

Out ( 𝒜 ) := Aut ( 𝒜 ) / Inn ( 𝒜 ) . assign Out 𝒜 Aut 𝒜 Inn 𝒜 \displaystyle\operatorname{Out}(\mathcal{A}):=\operatorname{Aut}(\mathcal{A})/% \operatorname{Inn}(\mathcal{A}). roman_Out ( caligraphic_A ) := roman_Aut ( caligraphic_A ) / roman_Inn ( caligraphic_A ) .
Definition 21 .

We denote by 𝒜 op superscript 𝒜 op \mathcal{A}^{\textup{op}} caligraphic_A start_POSTSUPERSCRIPT op end_POSTSUPERSCRIPT the opposite algebra: it is identical to 𝒜 𝒜 \mathcal{A} caligraphic_A as a vector space, but with opposite product:

a op b op = ( b a ) op . superscript 𝑎 op superscript 𝑏 op superscript 𝑏 𝑎 op a^{\textup{op}}b^{\textup{op}}=(ba)^{\textup{op}}. italic_a start_POSTSUPERSCRIPT op end_POSTSUPERSCRIPT italic_b start_POSTSUPERSCRIPT op end_POSTSUPERSCRIPT = ( italic_b italic_a ) start_POSTSUPERSCRIPT op end_POSTSUPERSCRIPT .

Here a op , b op superscript 𝑎 op superscript 𝑏 op a^{\textup{op}},b^{\textup{op}} italic_a start_POSTSUPERSCRIPT op end_POSTSUPERSCRIPT , italic_b start_POSTSUPERSCRIPT op end_POSTSUPERSCRIPT are the elements in 𝒜 op superscript 𝒜 op \mathcal{A}^{\textup{op}} caligraphic_A start_POSTSUPERSCRIPT op end_POSTSUPERSCRIPT corresponding to a , b 𝒜 𝑎 𝑏 𝒜 a,b\in\mathcal{A} italic_a , italic_b ∈ caligraphic_A , respectively.


Definition 1.2 .

Given a primitive n 𝑛 n italic_n th root θ n 𝑛 𝜃 \sqrt[n]{\theta} nth-root start_ARG italic_n end_ARG start_ARG italic_θ end_ARG of θ k 𝜃 𝑘 \theta\in k italic_θ ∈ italic_k and σ G k 𝜎 subscript 𝐺 𝑘 \sigma\in G_{k} italic_σ ∈ italic_G start_POSTSUBSCRIPT italic_k end_POSTSUBSCRIPT , then κ ( θ ) σ 𝜅 𝜃 𝜎 \kappa(\theta)\sigma italic_κ ( italic_θ ) italic_σ is the element of A 𝐴 A italic_A such that

σ θ n = ζ κ ( θ ) σ θ n . 𝜎 𝑛 𝜃 superscript 𝜁 𝜅 𝜃 𝜎 𝑛 𝜃 \sigma\sqrt[n]{\theta}=\zeta^{\kappa(\theta)\sigma}\sqrt[n]{\theta}. italic_σ nth-root start_ARG italic_n end_ARG start_ARG italic_θ end_ARG = italic_ζ start_POSTSUPERSCRIPT italic_κ ( italic_θ ) italic_σ end_POSTSUPERSCRIPT nth-root start_ARG italic_n end_ARG start_ARG italic_θ end_ARG .

Definition 2.1 .

[ 5 ] A right Leibniz algebra L 𝐿 L italic_L is a vector space over a field 𝕂 𝕂 \mathbb{K} blackboard_K endowed with a bilinear product [ , ] normal-⋅ normal-⋅ [\cdot,\cdot] [ ⋅ , ⋅ ] satisfying the Leibniz identity

[ [ y , z ] , x ] = [ [ y , x ] , z ] + [ y , [ z , x ] ] , 𝑦 𝑧 𝑥 𝑦 𝑥 𝑧 𝑦 𝑧 𝑥 [[y,z],x]=[[y,x],z]+[y,[z,x]], [ [ italic_y , italic_z ] , italic_x ] = [ [ italic_y , italic_x ] , italic_z ] + [ italic_y , [ italic_z , italic_x ] ] ,

for all x , y , z L 𝑥 𝑦 𝑧 𝐿 x,y,z\in L italic_x , italic_y , italic_z ∈ italic_L .

Definition 2.2 .

[ 1 ] A Leibniz triple system is a vector space T 𝑇 T italic_T endowed with a trilinear operation { , , } : T × T × T T normal-: normal-⋅ normal-⋅ normal-⋅ normal-→ 𝑇 𝑇 𝑇 𝑇 \{\cdot,\cdot,\cdot\}:T\times T\times T\rightarrow T { ⋅ , ⋅ , ⋅ } : italic_T × italic_T × italic_T → italic_T satisfying

{ a , { b , c , d } , e } = { { a , b , c } , d , e } - { { a , c , b } , d , e } - { { a , d , b } , c , e } + { { a , d , c } , b , e } , fragments { a , fragments { b , c , d } , e } { fragments { a , b , c } , d , e } { fragments { a , c , b } , d , e } { fragments { a , d , b } , c , e } { fragments { a , d , c } , b , e } , \displaystyle\{a,\{b,c,d\},e\}\!=\!\{\{a,b,c\},d,e\}\!-\!\{\{a,c,b\},d,e\}\!-% \!\{\{a,d,b\},c,e\}\!+\!\{\{a,d,c\},b,e\}, { italic_a , { italic_b , italic_c , italic_d } , italic_e } = { { italic_a , italic_b , italic_c } , italic_d , italic_e } - { { italic_a , italic_c , italic_b } , italic_d , italic_e } - { { italic_a , italic_d , italic_b } , italic_c , italic_e } + { { italic_a , italic_d , italic_c } , italic_b , italic_e } , (2.1)
{ a , b , { c , d , e } } = { { a , b , c } , d , e } - { { a , b , d } , c , e } - { { a , b , e } , c , d } + { { a , b , e } , d , c } , fragments { a , b , fragments { c , d , e } } { fragments { a , b , c } , d , e } { fragments { a , b , d } , c , e } { fragments { a , b , e } , c , d } { fragments { a , b , e } , d , c } , \displaystyle\{a,b,\{c,d,e\}\}\!=\!\{\{a,b,c\},d,e\}\!-\!\{\{a,b,d\},c,e\}\!-% \!\{\{a,b,e\},c,d\}\!+\!\{\{a,b,e\},d,c\}, { italic_a , italic_b , { italic_c , italic_d , italic_e } } = { { italic_a , italic_b , italic_c } , italic_d , italic_e } - { { italic_a , italic_b , italic_d } , italic_c , italic_e } - { { italic_a , italic_b , italic_e } , italic_c , italic_d } + { { italic_a , italic_b , italic_e } , italic_d , italic_c } , (2.2)

for all a , b , c , d , e T 𝑎 𝑏 𝑐 𝑑 𝑒 𝑇 a,b,c,d,e\in T italic_a , italic_b , italic_c , italic_d , italic_e ∈ italic_T .


Definition 2.1 (Class of symbols)

For any p , q 𝑝 𝑞 p,q\in\mathbb{N} italic_p , italic_q ∈ blackboard_N , define 𝒫 p , q subscript 𝒫 𝑝 𝑞 {\mathscr{P}}_{p,q} script_P start_POSTSUBSCRIPT italic_p , italic_q end_POSTSUBSCRIPT to be the space of homogeneous complex-valued polynomials on 𝒵 𝒵 {\mathscr{Z}} script_Z such that b 𝒫 p , q 𝑏 subscript 𝒫 𝑝 𝑞 b\in{\mathscr{P}}_{p,q} italic_b ∈ script_P start_POSTSUBSCRIPT italic_p , italic_q end_POSTSUBSCRIPT if and only if there exists a (unique) bounded operator b ~ ( p 𝒵 , q 𝒵 ) normal-~ 𝑏 superscript 𝑝 𝒵 superscript 𝑞 𝒵 \tilde{b}\in{\mathscr{L}}(\vee^{p}{\mathscr{Z}},\vee^{q}{\mathscr{Z}}) ~ start_ARG italic_b end_ARG ∈ script_L ( ∨ start_POSTSUPERSCRIPT italic_p end_POSTSUPERSCRIPT script_Z , ∨ start_POSTSUPERSCRIPT italic_q end_POSTSUPERSCRIPT script_Z ) such that for all z 𝒵 𝑧 𝒵 z\in{\mathscr{Z}} italic_z ∈ script_Z :

b ( z ) = z q , b ~ z p . 𝑏 𝑧 superscript 𝑧 tensor-product absent 𝑞 ~ 𝑏 superscript 𝑧 tensor-product absent 𝑝 \displaystyle b(z)={\langle}z^{\otimes q},\tilde{b}\,z^{\otimes p}{\rangle}\,. italic_b ( italic_z ) = ⟨ italic_z start_POSTSUPERSCRIPT ⊗ italic_q end_POSTSUPERSCRIPT , ~ start_ARG italic_b end_ARG italic_z start_POSTSUPERSCRIPT ⊗ italic_p end_POSTSUPERSCRIPT ⟩ . (9)

Definition 2.3 (Schensted’s column algorithm) .

Let a I 𝑎 normal-I a\in\mathrm{I} italic_a ∈ roman_I be a column and let x A 𝑥 𝐴 x\in A italic_x ∈ italic_A .

x a = { x a , if x a is a column; a y , 𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒 𝑥 𝑎 cases 𝑥 𝑎 if x a is a column; 𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒 superscript 𝑎 𝑦 𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒 𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒 x\cdot a=\begin{cases}xa,\,\mbox{if $xa$ is a column;}\\ a^{\prime}\cdot y,\,\mbox{otherwise}\end{cases} italic_x ⋅ italic_a = { start_ROW start_CELL italic_x italic_a , if italic_x italic_a is a column; end_CELL start_CELL end_CELL end_ROW start_ROW start_CELL italic_a start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ⋅ italic_y , otherwise end_CELL start_CELL end_CELL end_ROW

where y 𝑦 y italic_y is the rightmost letter in a 𝑎 a italic_a and is larger than or equal to x 𝑥 x italic_x , and a superscript 𝑎 normal-′ a^{\prime} italic_a start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT is obtained from a 𝑎 a italic_a by replacing y 𝑦 y italic_y with x 𝑥 x italic_x . We say that an element y 𝑦 y italic_y is connected to x 𝑥 x italic_x or simply that elements y 𝑦 y italic_y , x 𝑥 x italic_x are connected. And we will use the notation

x y := { 1 , iff x is connected to y , 0 , otherwise. 𝑥 𝑦 assign cases 1 iff x is connected to y , 𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒 0 otherwise. 𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒 x\rightleftarrows y:=\begin{cases}1,\mbox{ iff $x$ is connected to $y$,}\\ 0,\mbox{ otherwise.}\end{cases} italic_x ⇄ italic_y := { start_ROW start_CELL 1 , iff italic_x is connected to italic_y , end_CELL start_CELL end_CELL end_ROW start_ROW start_CELL 0 , otherwise. end_CELL start_CELL end_CELL end_ROW

Definition 4.6 .

Let ( M , c ) 𝑀 𝑐 (M,c) ( italic_M , italic_c ) be a conformal manifold of dimension at least 3, a Möbius surface or a Laplace curve. A regular curve γ : I M : 𝛾 𝐼 𝑀 \gamma:I\rightarrow M italic_γ : italic_I → italic_M is a parametrized conformal , resp. Möbius geodesic if any adapted Weyl structure \nabla (i.e., for which γ ˙ γ ˙ = 0 subscript ˙ 𝛾 ˙ 𝛾 0 \nabla_{\dot{\gamma}}\dot{\gamma}=0 ∇ start_POSTSUBSCRIPT ˙ start_ARG italic_γ end_ARG end_POSTSUBSCRIPT ˙ start_ARG italic_γ end_ARG = 0 ) satifies

h ( γ ˙ ) = 0 superscript ˙ 𝛾 0 h^{\nabla}(\dot{\gamma})=0 italic_h start_POSTSUPERSCRIPT ∇ end_POSTSUPERSCRIPT ( ˙ start_ARG italic_γ end_ARG ) = 0 (23)

on I 𝐼 I italic_I . It is an unparametrized conformal geodesic if the section of ν 𝜈 \nu italic_ν induced by h ( γ ˙ ) superscript ˙ 𝛾 h^{\nabla}(\dot{\gamma}) italic_h start_POSTSUPERSCRIPT ∇ end_POSTSUPERSCRIPT ( ˙ start_ARG italic_γ end_ARG ) vanishes identically.


Definition 111 .

Let X 𝑋 X italic_X be a topological space, and let a , b , c H i ( X , R ) 𝑎 𝑏 𝑐 superscript 𝐻 𝑖 𝑋 𝑅 a,b,c\in H^{i}(X,R) italic_a , italic_b , italic_c ∈ italic_H start_POSTSUPERSCRIPT italic_i end_POSTSUPERSCRIPT ( italic_X , italic_R ) be cohomology classes such that

a b = b c = 0 , 𝑎 𝑏 𝑏 𝑐 0 a\cup b=b\cup c=0, italic_a ∪ italic_b = italic_b ∪ italic_c = 0 ,

where R 𝑅 R italic_R is any ring of coefficients.

Then the triple Massey product < a , b , c > fragments a normal-, b normal-, c <a,b,c> < italic_a , italic_b , italic_c > is defined as follows: take cocycle representatives a , b , c superscript 𝑎 normal-′ superscript 𝑏 normal-′ superscript 𝑐 normal-′ a^{\prime},b^{\prime},c^{\prime} italic_a start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_b start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_c start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT for a , b , c , 𝑎 𝑏 𝑐 a,b,c, italic_a , italic_b , italic_c , respectively, and cochains x , y C 2 i - 1 ( X , R ) 𝑥 𝑦 superscript 𝐶 2 𝑖 1 𝑋 𝑅 x,y\in C^{2i-1}(X,R) italic_x , italic_y ∈ italic_C start_POSTSUPERSCRIPT 2 italic_i - 1 end_POSTSUPERSCRIPT ( italic_X , italic_R ) such that

d x = a b , d y = b c . formulae-sequence 𝑑 𝑥 superscript 𝑎 superscript 𝑏 𝑑 𝑦 superscript 𝑏 superscript 𝑐 dx=a^{\prime}\cup b^{\prime},dy=b^{\prime}\cup c^{\prime}. italic_d italic_x = italic_a start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ∪ italic_b start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT , italic_d italic_y = italic_b start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ∪ italic_c start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT .

Then < a , b , c > fragments a normal-, b normal-, c <a,b,c> < italic_a , italic_b , italic_c > is the class of

a y + ( - 1 ) i + 1 x c superscript 𝑎 𝑦 superscript 1 𝑖 1 𝑥 superscript 𝑐 a^{\prime}\cup y+(-1)^{i+1}x\cup c^{\prime} italic_a start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT ∪ italic_y + ( - 1 ) start_POSTSUPERSCRIPT italic_i + 1 end_POSTSUPERSCRIPT italic_x ∪ italic_c start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT

inside

H 3 i - 1 ( X , R ) / ( a H 2 i - 1 ( X , R ) + H 2 i - 1 ( X , R ) c ) . superscript 𝐻 3 𝑖 1 𝑋 𝑅 𝑎 superscript 𝐻 2 𝑖 1 𝑋 𝑅 superscript 𝐻 2 𝑖 1 𝑋 𝑅 𝑐 H^{3i-1}(X,R)/(a\cup H^{2i-1}(X,R)+H^{2i-1}(X,R)\cup c). italic_H start_POSTSUPERSCRIPT 3 italic_i - 1 end_POSTSUPERSCRIPT ( italic_X , italic_R ) / ( italic_a ∪ italic_H start_POSTSUPERSCRIPT 2 italic_i - 1 end_POSTSUPERSCRIPT ( italic_X , italic_R ) + italic_H start_POSTSUPERSCRIPT 2 italic_i - 1 end_POSTSUPERSCRIPT ( italic_X , italic_R ) ∪ italic_c ) .

Definition 1.2 .

Δ Δ \Delta roman_Δ is involutive if there is a 1-form η 𝜂 \eta italic_η such that k e r ( η ) = Δ 𝑘 𝑒 𝑟 𝜂 Δ ker(\eta)=\Delta italic_k italic_e italic_r ( italic_η ) = roman_Δ and

η d η = 0 . 𝜂 𝑑 𝜂 0 \eta\wedge d\eta=0. italic_η ∧ italic_d italic_η = 0 .

Definition 2.2 .

A hom-Leibniz algebra is a triple ( 𝔤 , [ , ] , α ) 𝔤 normal-⋅ normal-⋅ 𝛼 (\mathfrak{g},[\cdot,\cdot],\alpha) ( fraktur_g , [ ⋅ , ⋅ ] , italic_α ) consisting of a vector space 𝔤 𝔤 \mathfrak{g} fraktur_g , a bilinear map (bracket) [ , ] : 2 𝔤 𝔤 normal-: normal-⋅ normal-⋅ normal-⟶ superscript 2 𝔤 𝔤 [\cdot,\cdot]:\wedge^{2}\mathfrak{g}\longrightarrow\mathfrak{g} [ ⋅ , ⋅ ] : ∧ start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT fraktur_g ⟶ fraktur_g and an algebra endomorphism α : 𝔤 𝔤 normal-: 𝛼 normal-→ 𝔤 𝔤 \alpha:\mathfrak{g}\,\rightarrow\,\mathfrak{g} italic_α : fraktur_g → fraktur_g satisfying the following hom-Leibniz rule

[ α ( x ) , [ y , z ] ] = [ [ x , y ] , α ( z ) ] + [ α ( y ) , [ x , z ] ] , x , y , z 𝔤 . formulae-sequence 𝛼 𝑥 𝑦 𝑧 𝑥 𝑦 𝛼 𝑧 𝛼 𝑦 𝑥 𝑧 for-all 𝑥 𝑦 𝑧 𝔤 [\alpha(x),[y,z]]=[[x,y],\alpha(z)]+[\alpha(y),[x,z]],\quad\forall x,y,z\in% \mathfrak{g}. [ italic_α ( italic_x ) , [ italic_y , italic_z ] ] = [ [ italic_x , italic_y ] , italic_α ( italic_z ) ] + [ italic_α ( italic_y ) , [ italic_x , italic_z ] ] , ∀ italic_x , italic_y , italic_z ∈ fraktur_g . (3)

Definition 3.5 (Minimal Acceleration Cost) .

For all measures 𝝁 1 , 𝝁 2 𝒫 2 ( 𝐑 2 d ) superscript 𝝁 1 superscript 𝝁 2 subscript 𝒫 2 superscript 𝐑 2 𝑑 {\boldsymbol{\mu}}^{1},{\boldsymbol{\mu}}^{2}\in{\mathscr{P}}_{2}({\mathbf{R}}% ^{2d}) bold_italic_μ start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT , bold_italic_μ start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT ∈ script_P start_POSTSUBSCRIPT 2 end_POSTSUBSCRIPT ( bold_R start_POSTSUPERSCRIPT 2 italic_d end_POSTSUPERSCRIPT ) let ADM ( 𝝁 1 , 𝝁 2 ) ADM superscript 𝝁 1 superscript 𝝁 2 {\mathrm{ADM}}({\boldsymbol{\mu}}^{1},{\boldsymbol{\mu}}^{2}) roman_ADM ( bold_italic_μ start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT , bold_italic_μ start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT ) denote the set of transport plans 𝝎 𝒫 ( 𝐑 4 d ) 𝝎 𝒫 superscript 𝐑 4 𝑑 {\boldsymbol{\omega}}\in{\mathscr{P}}({\mathbf{R}}^{4d}) bold_italic_ω ∈ script_P ( bold_R start_POSTSUPERSCRIPT 4 italic_d end_POSTSUPERSCRIPT ) with

( 𝕡 1 , 𝕡 2 ) # 𝝎 = 𝝁 1 and ( 𝕡 3 , 𝕡 4 ) # 𝝎 = 𝝁 2 . formulae-sequence superscript 𝕡 1 superscript 𝕡 2 # 𝝎 superscript 𝝁 1 and superscript 𝕡 3 superscript 𝕡 4 # 𝝎 superscript 𝝁 2 ({\mathbbm{p}}^{1},{\mathbbm{p}}^{2})\#{\boldsymbol{\omega}}={\boldsymbol{\mu}% }^{1}\quad\text{and}\quad({\mathbbm{p}}^{3},{\mathbbm{p}}^{4})\#{\boldsymbol{% \omega}}={\boldsymbol{\mu}}^{2}. ( blackboard_p start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT , blackboard_p start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT ) # bold_italic_ω = bold_italic_μ start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT and ( blackboard_p start_POSTSUPERSCRIPT 3 end_POSTSUPERSCRIPT , blackboard_p start_POSTSUPERSCRIPT 4 end_POSTSUPERSCRIPT ) # bold_italic_ω = bold_italic_μ start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT .

The minimal acceleration cost is the functional A τ subscript A 𝜏 {\mathrm{A}}_{\tau} roman_A start_POSTSUBSCRIPT italic_τ end_POSTSUBSCRIPT defined by

A τ ( 𝝁 1 , 𝝁 2 ) 2 := inf { 𝐑 4 d a τ ( 𝒙 1 , 𝒙 2 ) 2 𝝎 ( d 𝒙 1 , d 𝒙 2 ) : 𝝎 ADM ( 𝝁 1 , 𝝁 2 ) } . assign subscript A 𝜏 superscript superscript 𝝁 1 superscript 𝝁 2 2 infimum conditional-set subscript superscript 𝐑 4 𝑑 subscript 𝑎 𝜏 superscript superscript 𝒙 1 superscript 𝒙 2 2 𝝎 𝑑 superscript 𝒙 1 𝑑 superscript 𝒙 2 𝝎 ADM superscript 𝝁 1 superscript 𝝁 2 {\mathrm{A}}_{\tau}({\boldsymbol{\mu}}^{1},{\boldsymbol{\mu}}^{2})^{2}:=\inf% \Bigg{\{}\int_{{\mathbf{R}}^{4d}}a_{\tau}({\boldsymbol{x}}^{1},{\boldsymbol{x}% }^{2})^{2}\,{\boldsymbol{\omega}}(d{\boldsymbol{x}}^{1},d{\boldsymbol{x}}^{2})% \colon{\boldsymbol{\omega}}\in{\mathrm{ADM}}({\boldsymbol{\mu}}^{1},{% \boldsymbol{\mu}}^{2})\Bigg{\}}. roman_A start_POSTSUBSCRIPT italic_τ end_POSTSUBSCRIPT ( bold_italic_μ start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT , bold_italic_μ start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT ) start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT := roman_inf { ∫ start_POSTSUBSCRIPT bold_R start_POSTSUPERSCRIPT 4 italic_d end_POSTSUPERSCRIPT end_POSTSUBSCRIPT italic_a start_POSTSUBSCRIPT italic_τ end_POSTSUBSCRIPT ( bold_italic_x start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT , bold_italic_x start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT ) start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT bold_italic_ω ( italic_d bold_italic_x start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT , italic_d bold_italic_x start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT ) : bold_italic_ω ∈ roman_ADM ( bold_italic_μ start_POSTSUPERSCRIPT 1 end_POSTSUPERSCRIPT , bold_italic_μ start_POSTSUPERSCRIPT 2 end_POSTSUPERSCRIPT ) } . (3.4)