diff --git a/experimental/AlgebraicShifting/src/UniformHypergraph.jl b/experimental/AlgebraicShifting/src/UniformHypergraph.jl index 286ec50b163..e79e8a455b7 100644 --- a/experimental/AlgebraicShifting/src/UniformHypergraph.jl +++ b/experimental/AlgebraicShifting/src/UniformHypergraph.jl @@ -52,6 +52,8 @@ function Base.:(==)(K :: UniformHypergraph, L :: UniformHypergraph) end raw""" Alexander dual, seen as bijection ``\binom{[n]}{k} \to \binom{[n]}{n-k}`` """ -function alexander_dual(K :: UniformHypergraph) +function alexander_dual(K::UniformHypergraph) return uniform_hypergraph(alexander_dual(simplicial_complex([[[i] for i in 1:K.n_vertices]; K.faces])), K.n_vertices - K.k) end + +is_shifted(K::UniformHypergraph) = is_shifted(simplicial_complex(K)) diff --git a/src/Combinatorics/SimplicialComplexes.jl b/src/Combinatorics/SimplicialComplexes.jl index d0dd8bbe61b..6aa1ed554af 100644 --- a/src/Combinatorics/SimplicialComplexes.jl +++ b/src/Combinatorics/SimplicialComplexes.jl @@ -710,3 +710,7 @@ end function barycentric_subdivision(K::SimplicialComplex) return SimplicialComplex(Polymake.topaz.barycentric_subdivision(pm_object(K))) end + +function is_shifted(K::SimplicialComplex) + return pm_object(K).SHIFTED +end diff --git a/src/exports.jl b/src/exports.jl index 576e3384795..2cd0483b0e1 100644 --- a/src/exports.jl +++ b/src/exports.jl @@ -899,6 +899,7 @@ export is_right export is_semiregular export is_semisimple export is_semistandard +export is_shifted export is_simple, has_is_simple, set_is_simple export is_simplicial export is_singular