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rework group actions

This commit is contained in:
kalmarek 2020-06-23 16:13:42 +02:00
parent b9a30f02c7
commit 0778f828e4
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2 changed files with 36 additions and 59 deletions

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@ -186,25 +186,19 @@ function (g::GroupRingElem)(y::GroupRingElem)
return res
end
###############################################################################
#
# perm actions
#
###############################################################################
function (g::Generic.Perm)(y::GroupRingElem)
function (g::GroupElem)(y::GroupRingElem)
RG = parent(y)
result = zero(RG, eltype(y.coeffs))
for (idx, c) in enumerate(y.coeffs)
if c!= zero(eltype(y.coeffs))
if !iszero(c)
result[g(RG.basis[idx])] = c
end
end
return result
end
function (g::Generic.Perm)(y::GroupRingElem{T, <:SparseVector}) where T
function (g::GroupElem)(y::GroupRingElem{T, <:SparseVector}) where T
RG = parent(y)
index = [RG.basis_dict[g(RG.basis[idx])] for idx in y.coeffs.nzind]
@ -213,6 +207,12 @@ function (g::Generic.Perm)(y::GroupRingElem{T, <:SparseVector}) where T
return result
end
###############################################################################
#
# perm && WreathProductElems actions: MatAlgElem
#
###############################################################################
function (p::Generic.Perm)(A::MatAlgElem)
length(p.d) == size(A, 1) == size(A,2) || throw("Can't act via $p on matrix of size $(size(A))")
result = similar(A)
@ -224,24 +224,6 @@ function (p::Generic.Perm)(A::MatAlgElem)
return result
end
###############################################################################
#
# WreathProductElems action on MatAlgElem
#
###############################################################################
function (g::WreathProductElem)(y::GroupRingElem)
RG = parent(y)
result = zero(RG, eltype(y.coeffs))
for (idx, c) in enumerate(y.coeffs)
if c!= zero(eltype(y.coeffs))
result[g(RG.basis[idx])] = c
end
end
return result
end
function (g::WreathProductElem{N})(A::MatAlgElem) where N
# @assert N == size(A,1) == size(A,2)
flips = ntuple(i->(g.n[i].d[1]==1 && g.n[i].d[2]==2 ? 1 : -1), N)
@ -257,8 +239,6 @@ function (g::WreathProductElem{N})(A::MatAlgElem) where N
else
result[g.p[i], g.p[j]] = -x
end
# result[i, j] = AbstractAlgebra.mul!(x, x, flips[i]*flips[j])
# this mul! needs to be separately defined, but is 2x faster
end
end
return result
@ -266,33 +246,33 @@ end
###############################################################################
#
# Action of WreathProductElems on AutGroupElem
# perm && WreathProductElems actions: Automorphism
#
###############################################################################
function AutFG_emb(A::AutGroup, g::WreathProductElem)
function (g::GroupElem)(a::Automorphism)
Ag = parent(a)(g)
Ag_inv = inv(Ag)
res = append!(Ag, a, Ag_inv)
return Groups.freereduce!(res)
end
(A::AutGroup)(p::Generic.Perm) = A(Groups.AutSymbol(p))
function (A::AutGroup)(g::WreathProductElem)
isa(A.objectGroup, FreeGroup) || throw("Not an Aut(Fₙ)")
parent(g).P.n == length(A.objectGroup.gens) || throw("No natural embedding of $(parent(g)) into $A")
elt = one(A)
Id = one(parent(g.n.elts[1]))
flips = Groups.AutSymbol[Groups.flip_autsymbol(i) for i in 1:length(g.p.d) if g.n.elts[i] != Id]
Groups.r_multiply!(elt, flips, reduced=false)
Groups.r_multiply!(elt, [Groups.perm_autsymbol(g.p)])
for i in 1:length(g.p.d)
if g.n.elts[i] != Id
push!(elt, Groups.flip(i))
end
end
push!(elt, Groups.AutSymbol(g.p))
return elt
end
function (g::WreathProductElem)(a::Groups.Automorphism)
A = parent(a)
g_emb = AutFG_emb(A,g)
res = deepcopy(g_emb)
res = Groups.r_multiply!(res, a.symbols, reduced=false)
res = Groups.r_multiply!(res, [inv(s) for s in reverse!(g_emb.symbols)])
return res
end
function (p::Generic.Perm)(a::Groups.Automorphism)
res = parent(a)(Groups.perm_autsymbol(p))
res = Groups.r_multiply!(res, a.symbols, reduced=false)
res = Groups.r_multiply!(res, [Groups.perm_autsymbol(inv(p))])
return res
end
# fallback:
Base.one(p::Generic.Perm) = Perm(length(p.d))

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@ -3,12 +3,9 @@
ssgs(M::MatAlgebra, i, j) = (S = [Eij(M, i, j), Eij(M, j, i)];
S = unique([S; inv.(S)]); S)
rmul = Groups.rmul_autsymbol
lmul = Groups.lmul_autsymbol
function ssgs(A::AutGroup, i, j)
rmuls = [rmul(i,j), rmul(j,i)]
lmuls = [lmul(i,j), lmul(j,i)]
rmuls = [Groups.transvection_R(i,j), Groups.transvection_R(j,i)]
lmuls = [Groups.transvection_L(i,j), Groups.transvection_L(j,i)]
gen_set = A.([rmuls; lmuls])
return unique([gen_set; inv.(gen_set)])
end
@ -33,7 +30,7 @@
elt2 = E_R[rand(sizes[1]:sizes[2])]
y = 2RG(elt2) - RG(elt)
for G in [PermGroup(N), WreathProduct(PermGroup(2), PermGroup(N))]
for G in [SymmetricGroup(N), WreathProduct(SymmetricGroup(2), SymmetricGroup(N))]
@test all(g(one(M)) == one(M) for g in G)
@test all(rdict[g(m)] <= sizes[1] for g in G for m in S)
@test all(g(m)*g(n) == g(m*n) for g in G for m in S for n in S)
@ -50,9 +47,9 @@
Sij = ssgs(M, i,j)
Δij= PropertyT.spLaplacian(RG, Sij)
@test all(p(Δij) == PropertyT.spLaplacian(RG, ssgs(M, p[i], p[j])) for p in PermGroup(N))
@test all(p(Δij) == PropertyT.spLaplacian(RG, ssgs(M, p[i], p[j])) for p in SymmetricGroup(N))
@test all(g(Δij) == PropertyT.spLaplacian(RG, ssgs(M, g.p[i], g.p[j])) for g in WreathProduct(PermGroup(2), PermGroup(N)))
@test all(g(Δij) == PropertyT.spLaplacian(RG, ssgs(M, g.p[i], g.p[j])) for g in WreathProduct(SymmetricGroup(2), SymmetricGroup(N)))
end
end
end
@ -79,7 +76,7 @@ end
elt2 = E_R[rand(sizes[1]:sizes[2])]
y = 2RG(elt2) - RG(elt)
for G in [PermGroup(N), WreathProduct(PermGroup(2), PermGroup(N))]
for G in [SymmetricGroup(N), WreathProduct(SymmetricGroup(2), SymmetricGroup(N))]
@test all(g(one(M)) == one(M) for g in G)
@test all(rdict[g(m)] <= sizes[1] for g in G for m in S)
@test all(g(m)*g(n) == g(m*n) for g in G for m in S for n in S)
@ -95,9 +92,9 @@ end
Sij = ssgs(M, i,j)
Δij= PropertyT.spLaplacian(RG, Sij)
@test all(p(Δij) == PropertyT.spLaplacian(RG, ssgs(M, p[i], p[j])) for p in PermGroup(N))
@test all(p(Δij) == PropertyT.spLaplacian(RG, ssgs(M, p[i], p[j])) for p in SymmetricGroup(N))
@test all(g(Δij) == PropertyT.spLaplacian(RG, ssgs(M, g.p[i], g.p[j])) for g in WreathProduct(PermGroup(2), PermGroup(N)))
@test all(g(Δij) == PropertyT.spLaplacian(RG, ssgs(M, g.p[i], g.p[j])) for g in WreathProduct(SymmetricGroup(2), SymmetricGroup(N)))
end
end