mathlib

5ed51dc3 - feat(algebraic_topology): variations on the statements of simplicial relations (#16957)

feat(algebraic_topology): variations on the statements of simplicial relations (#16957) This PR introduces variations on the statements of simplicial relations which makes it easier to use. This is demonstrated in `algebraic_topology.dold_kan.faces`. The attribute `reassoc` is also added to the simplicial relations.