Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

changed compose in src/Groups ... #1038

Merged
merged 1 commit into from
Feb 2, 2022
Merged

changed compose in src/Groups ... #1038

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion docs/src/Groups/grouphom.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -118,7 +118,7 @@ Oscar supports the following operations on homomorphisms.
* `f^n` = the homomorphism `f` composed `n` times with itself.
An exception is thrown if the domain and the codomain of `f` do not coincide
(unless `n=1`). If `n` is negative, the result is the inverse of `f` composed `n` times with itself.
* `compose(g,f)` = composition of `g` and `f`. This works only if the codomain of `g` coincide with the domain of `f`. Shorter equivalent expressions are `g*f` and `f(g)`.
* `compose(f, g)` = composition of `f` and `g`. This works only if the codomain of `f` coincides with the domain of `g`. Shorter equivalent expressions are `f*g` and `g(f)`.

**Example:**
```jldoctest
Expand Down
6 changes: 3 additions & 3 deletions src/Groups/homomorphisms.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ function ==(f::GAPGroupHomomorphism{S,T}, g::GAPGroupHomomorphism{S,T}) where S
return f.map == g.map
end

Base.:*(f::GAPGroupHomomorphism{S, T}, g::GAPGroupHomomorphism{T, U}) where S where T where U = compose(g, f)
Base.:*(f::GAPGroupHomomorphism{S, T}, g::GAPGroupHomomorphism{T, U}) where S where T where U = compose(f, g)

function Base.inv(f::GAPGroupHomomorphism{S,T}) where S where T
@assert GAPWrap.IsBijective(f.map) "f is not bijective"
Expand All @@ -55,15 +55,15 @@ function Base.:^(f::GAPGroupHomomorphism{S,T}, n::Int64) where S where T
end
end

function compose(g::GAPGroupHomomorphism{T, U}, f::GAPGroupHomomorphism{S, T}) where S where T where U
function compose(f::GAPGroupHomomorphism{S, T}, g::GAPGroupHomomorphism{T, U}) where {S, T, U}
dom = domain(f)
cod = codomain(g)
@assert codomain(f) == domain(g)
mp = GAP.Globals.CompositionMapping(g.map, f.map)
return GAPGroupHomomorphism(dom, cod, mp)
end

#(g::GAPGroupHomomorphism{T, U})(f::GAPGroupHomomorphism{S, T}) where {S,T,U} = compose(g,f)
#(g::GAPGroupHomomorphism{T, U})(f::GAPGroupHomomorphism{S, T}) where {S,T,U} = compose(f,g)

"""
id_hom(G::GAPGroup)
Expand Down
6 changes: 3 additions & 3 deletions src/Groups/sub.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -324,7 +324,7 @@ function quo(::Type{Q}, G::T, elements::Vector{S}) where {Q <: GAPGroup, T <: GA
F, epi = quo(G, elements)
if !(F isa Q)
F, map = isomorphic_group(Q, F)
epi = compose(map, epi)
epi = compose(epi, map)
end
return F, epi
end
Expand Down Expand Up @@ -373,7 +373,7 @@ function quo(::Type{Q}, G::T, N::T) where {Q <: GAPGroup, T <: GAPGroup}
F, epi = quo(G, N)
if !(F isa Q)
F, map = isomorphic_group(Q, F)
epi = compose(map, epi)
epi = compose(epi, map)
end
return F, epi
end
Expand Down Expand Up @@ -426,7 +426,7 @@ function maximal_abelian_quotient(::Type{Q}, G::GAPGroup) where Q <: GAPGroup
F, epi = maximal_abelian_quotient(G)
if !(F isa Q)
F, map = isomorphic_group(Q, F)
epi = compose(map, epi)
epi = compose(epi, map)
end
return F, epi
end
Expand Down
9 changes: 9 additions & 0 deletions test/Groups/homomorphisms.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -314,3 +314,12 @@ end
@test isisomorphic(A,GL(2,3))[1]
@test order(inner_automorphisms_group(A)[1])==1
end

@testset "Composition of mappings" begin
g = symmetric_group(4)
q, epi = quo(g, pcore(g, 2)[1])
F, iso = isomorphic_perm_group(q)
comp = compose(epi, iso)
@test domain(comp) == domain(epi)
@test codomain(comp) == codomain(iso)
end