[ add ] Algebra.Construct.Centre.X of an algebra X, following #2863
#2885
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JacquesCarette
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Nov 21, 2025
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Only change needed: delete commented out code.
This was referenced Nov 21, 2025
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This PR is a clean do-over of #2863 , avoiding any dependency/coupling on
either #2872 or#2854 .Issues:
Centreof aGroupetc. #2863 ie. the centre of aGroupis defined in terms of the centre of its underlyingMonoid, iterated down as far as a bareCentertype based on the (components of) an underlyingRawMagma.Sub.X(eg as in [ draft ] Alternative design for sub- and quotient-(Abelian)Groups #2859 ) until the discussion on that PR and Normal subgroups and quotient groups #2854 stabilises with an agreed hierarchy for such sub-algebras.Relation.Binary.Morphism.Construct.On#2872 and/or [ rename/deprecate ] RenameAlgebra.Properties.Monoid.ε-comm#2883 get merged, etc. UPDATED: DONEAlgebra.Construct.Centre.Ring(and develop the infrastructure for the 'missing' intermediate algebras...)NB. the hierarchy of
IsXMonomorphismstructures unfortunately (;-)/!?) goes against the grain of how these things are all built up successively here, so downstream we might think about refactoring that hierarchy, or else introducing more 'smart' constructors for such things.