### 7.7.19 nchomolog_lib

Status: experimental

Library:
  nchomolog.lib
Purpose:
  Procedures for Noncommutative Homological Algebra
Authors:
  Viktor Levandovskyy levandov@math.rwth-aachen.de,
  Christian Schilli, christian.schilli@rwth-aachen.de,
  Gerhard Pfister, pfister@mathematik.uni-kl.de

Overview:
  In this library we present tools of homological algebra for finitely presented modules over GR-algebras.

Procedures:

> 7.7.19.0. ncExt_R |  | computes presentation of Ext^k(M',R), M module, R basering, M'=coker(M)
> 7.7.19.0. ncHom |  | computes presentation of Hom(M',N'), M,N modules, M'=coker(M), N'=coker(N)
> 7.7.19.0. coHom |  | computes presentation of Hom(R^k,A), A matrix over basering R
> 7.7.19.0. contraHom |  | computes presentation of Hom(A,R^k), A matrix over basering R
> 7.7.19.0. dmodoublext |  | computes presentation of Ext_D^i(Ext_D^i(M,D),D), where D is a basering
> 7.7.19.0. is_cenBimodule |  | checks whether a module presented by M is Artin-centralizing
> 7.7.19.0. is_cenSubbimodule |  | checks whether a subbimodule M is Artin-centralizing

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