CompletedGroupAlgebra.AllFiniteAugmentation

5 sections | 5 files | 37 declarations

This module develops completed group algebras through finite quotient stages, transition maps, coefficient change, augmentation, comparison maps, and inverse-limit topology.

AugmentationIdeal

1 files | 14 declarations | 13 Theorem | 1 Definition
The canonical augmentation ideal \(I_G\subseteq \widehat{R[G]}\) is the kernel of the completed augmentation \(\varepsilon:\widehat{R[G]}\to R\).

CanonicalAugmentation

1 files | 13 declarations | 11 Theorem | 2 Definition
The completed augmentation evaluated at a finite stage.

InClassComparison

1 files | 2 declarations | 2 Theorem
Completed Group Algebra / All Finite Augmentation / Within a Class Comparison.

StageAugmentation

1 files | 7 declarations | 6 Theorem | 1 Definition
The augmentation map on a finite stage is the ring homomorphism \(R[G/U]\to R\) that sends every group-like basis element to \(1\).

TerminalIndex

1 files | 1 declarations | 1 Instance
The finite quotient index type is nonempty, witnessed by the terminal quotient or canonical base object.