resolution M
res M
The given generators and relations are used to determine a presentation of M to serve as the first matrix of the free resolution; if the presentation is not minimal, and a minimal resolution is desired, use resolution minimalPresentation M instead.
Warning: the resolution can have free modules with unexpected ranks when the module M is not homogeneous. Here is an example where even the lengths of the resolutions differ. We compute a resolution of the kernel of a ring map in two ways. The ring R is constructed naively, but the ring S is constructed with variables of the right degrees so the ring map g will turn out to be homogeneous.
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A manually constructed resolution can be installed as the resolution of a module, bypassing the call to the engine when a resolution is requested, as follows.
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For an overview of resolutions, in order of increasing detail, see: