Free Resolutions and Change of Rings Original Research Article 195-213 Srikanth Iyengar Close Close preview | Purchase PDF (270 K) | Related articles | Related reference work articles AbstractAbstract | ReferencesReferences Abstract Projective r

Projective resolutions of modules over a ringRare constructed starting from appropriate projective resolutions over a ringQmapping toR. It is shown that such resolutions may be chosen to be minimal in codimension ≤2, but not in codimension 3. This is used to obtain minimal resolutions for essentially all modules over local (or graded) ringsRwith codimension ≤2. Explicit resolutions are given for cyclic modules over multigraded rings, and necessary and sufficient conditions are obtained for their minimality.