Macaulay2 » Documentation
Packages » SimplicialModules :: SimplicialModule
next | previous | forward | backward | up | index | toc

SimplicialModule -- the class of all simplicial modules

Description

A simplicial R-module is a presheaf on the so-called Simplex Category, with values in the category of R-modules. Concretely, such objects can be viewed as nonnegatively graded R-modules equipped with certain face and degeneracy operators satisfying the simplicial identities. As an example, every R-module M can be converted into a simplicial R-module whose degree n piece is equal to M for all n, and with face/degeneracy operators simply given by the identity.

i1 : S = simplicialModule(ZZ^2,3,Degeneracy => true) --the integer 3 specifies a top degree, the option Degeneracy specifies whether or not to compute degeneracy maps

       2       2       2       2
o1 = ZZ  <-- ZZ  <-- ZZ  <-- ZZ <-- ...
                              
     0       1       2       3

o1 : SimplicialModule

The output string for a simplicial module is meant to indicate that this object is infinite in general, and the user can only compute a finite snapshot of the object. The face/degeneracy maps can be accessed using the keys dd and ss, respectively. In order to verify that the resulting face/degeneracy maps satisfy the simplicial identities, one can use the isSimplicialModule command.

i2 : keys S

o2 = {complexLength, module, ss, dd, ring, complex, topDegree, cache}

o2 : List

See also

Functions and methods returning a Simplicial Module:

Methods that use a Simplicial Module:

For the programmer

The object SimplicialModule is a type, with ancestor classes MutableHashTable < HashTable < Thing.


The source of this document is in /build/reproducible-path/macaulay2-1.26.05+ds/M2/Macaulay2/packages/SimplicialModules/SimplicialModuleDOC.m2:161:0.