diff --git a/docs/src/Groups/matgroup.md b/docs/src/Groups/matgroup.md index 92a60cb518fc..6d7cf9347cd9 100644 --- a/docs/src/Groups/matgroup.md +++ b/docs/src/Groups/matgroup.md @@ -83,7 +83,7 @@ lower_triangular_matrix(L) conjugate_transpose(x::MatElem{T}) where T <: FinFieldElem complement(V::AbstractAlgebra.Generic.FreeModule{T}, W::AbstractAlgebra.Generic.Submodule{T}) where T <: FieldElem permutation_matrix(F::Ring, Q::AbstractVector{<:IntegerUnion}) -is_skewsymmetric_matrix(B::MatElem{T}) where T <: RingElem +is_alternating(B::MatElem) is_hermitian(B::MatElem{T}) where T <: FinFieldElem ``` diff --git a/src/Groups/matrices/forms.jl b/src/Groups/matrices/forms.jl index 5651c7361989..c4af34fce75f 100644 --- a/src/Groups/matrices/forms.jl +++ b/src/Groups/matrices/forms.jl @@ -26,7 +26,7 @@ mutable struct SesquilinearForm{T<:RingElem} elseif sym==:symmetric @assert is_symmetric(B) "The matrix is not symmetric" elseif sym==:alternating - @assert is_skewsymmetric_matrix(B) "The matrix is not skew-symmetric" + @assert is_alternating(B) "The matrix does not correspond to an alternating form" elseif sym != :quadratic error("Unsupported description") end diff --git a/src/Groups/matrices/matrix_manipulation.jl b/src/Groups/matrices/matrix_manipulation.jl index 9af03cb9111c..8db452851600 100644 --- a/src/Groups/matrices/matrix_manipulation.jl +++ b/src/Groups/matrices/matrix_manipulation.jl @@ -160,15 +160,15 @@ permutation_matrix(F::Ring, p::PermGroupElem) = permutation_matrix(F, Vector(p)) # ######################################################################## -# TODO: not sure whether this definition of skew-symmetric is standard (for fields of characteristic 2) +# TODO: Move to AbstractAlgebra """ - is_skewsymmetric_matrix(B::MatElem{T}) where T <: Ring + is_alternating(B::MatElem) -Return whether the matrix `B` is skew-symmetric, +Return whether the form corresponding to the matrix `B` is alternating, i.e. `B = -transpose(B)` and `B` has zeros on the diagonal. Return `false` if `B` is not a square matrix. """ -function is_skewsymmetric_matrix(B::MatElem{T}) where T <: RingElem +function is_alternating(B::MatElem) n = nrows(B) n==ncols(B) || return false diff --git a/src/aliases.jl b/src/aliases.jl index fd51087f455a..0686c53519f8 100644 --- a/src/aliases.jl +++ b/src/aliases.jl @@ -61,7 +61,6 @@ @alias issemisimple is_semisimple @alias issimplicial is_simplicial @alias issingular is_singular -@alias isskewsymmetric_matrix is_skewsymmetric_matrix @alias issmooth_curve is_smooth_curve @alias issolvable is_solvable @alias issupersolvable is_supersolvable diff --git a/src/exports.jl b/src/exports.jl index 1b5ae5796938..72587a97a537 100644 --- a/src/exports.jl +++ b/src/exports.jl @@ -800,7 +800,6 @@ export is_semisimple export is_simple, has_is_simple, set_is_simple export is_simplicial export is_singular -export is_skewsymmetric_matrix export is_smooth export is_solvable, has_is_solvable, set_is_solvable export is_sporadic_simple, has_is_sporadic_simple, set_is_sporadic_simple diff --git a/test/Groups/forms.jl b/test/Groups/forms.jl index 058f51893011..f46fa4fe26b9 100644 --- a/test/Groups/forms.jl +++ b/test/Groups/forms.jl @@ -3,7 +3,7 @@ F,z = FiniteField(t^2+1,"z") B = matrix(F,4,4,[0 1 0 0; 2 0 0 0; 0 0 0 z+2; 0 0 1-z 0]) - @test is_skewsymmetric_matrix(B) + @test is_alternating(B) f = alternating_form(B) @test f isa SesquilinearForm @test gram_matrix(f)==B @@ -473,7 +473,7 @@ end end B = Oscar.invariant_quadratic_form(G) @testset for g in gens(G) - @test is_skewsymmetric_matrix(g.elm*B*transpose(g.elm)-B) + @test is_alternating(g.elm*B*transpose(g.elm)-B) end G = GU(4,5) diff --git a/test/Groups/operations.jl b/test/Groups/operations.jl index 0e27ed224f99..77b7fe87f88c 100644 --- a/test/Groups/operations.jl +++ b/test/Groups/operations.jl @@ -80,16 +80,19 @@ end @test f(identity_matrix(F,6))==f(1)*identity_matrix(F,6) @test_throws ArgumentError conjugate_transpose(x) @test is_symmetric(P+transpose(P)) - @test is_skewsymmetric_matrix(P-transpose(P)) + @test is_skew_symmetric(P-transpose(P)) + @test is_alternating(P-transpose(P)) F,z = FiniteField(2,2) x=matrix(F,4,4,[1,z,0,0,0,1,z^2,z,z,0,0,1,0,0,z+1,0]) y=x+transpose(x) @test is_symmetric(y) @test is_hermitian(x+conjugate_transpose(x)) - @test is_skewsymmetric_matrix(y) + @test is_skew_symmetric(y) + @test is_alternating(y) y[1,1]=1 - @test !is_skewsymmetric_matrix(y) + @test is_skew_symmetric(y) + @test !is_alternating(y) @test conjugate_transpose(x)==transpose(matrix(F,4,4,[1,z+1,0,0,0,1,z,z+1,z+1,0,0,1,0,0,z,0])) end