id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
17160 Finitely generated axiom for (mutiplicative) magmas, semigroups, monoids, groups nthiery "This introduce an axiom FinitelyGeneratedAsMagma, as well as related
categories with axioms for magmas, semigroups and groups::
{{{
sage: Groups().FinitelyGeneratedAsMagma()
Category of finitely generated groups
}}}
For ease of notations, when there is no ambiguity, one can do::
{{{
sage: Groups().FinitelyGenerated()
Category of finitely generated groups
}}}
One motivation for this change (for #8678) is that finite semigroups
in Sage used to be automatically endowed with an `EnumeratedSets`
structure; the default enumeration is then obtained by iteratively
multiplying the semigroup generators. This forced any finite semigroup
to either implement an enumeration, or provide semigroup generators;
this was often inconvenient.
Instead, finite semigroups that provide a distinguished finite set of
generators with `semigroup_generators` should now explicitly declare
themselves in the category of `FinitelyGeneratedSemigroups`:
{{{
sage: Semigroups().FinitelyGenerated()
Category of finitely generated semigroups
}}}
This is a backward incompatible change.
TODO:
- Use the occasion to migrate TransitiveIdeal to RecursivelyEnumeratedSet" enhancement closed major sage-6.6 categories fixed days64 tscrim sage-combinat darij virmaux Nicolas M. Thiéry Travis Scrimshaw N/A 19ceb8124d27ba0124fb08a232c05924bb7114b0 19ceb8124d27ba0124fb08a232c05924bb7114b0 #10668 #15852