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Macaulay2Doc :: source(ChainComplexMap)

source(ChainComplexMap) -- find the source of a map of chain complexes

Synopsis

Description

In the example below, we have a map between two modules and extend it to a map between projective resolutions of the two modules. Then source gives the source of the map of chain complexes.
i1 : R = ZZ[x,y,z];
i2 : M = R^1/(x,y,z);
i3 : N = R^1/(x^2,y^2,x*y*z,z^2);
i4 : g = map(N,M,x*y);

o4 : Matrix
i5 : f = res g;
i6 : source f

      1      3      3      1
o6 = R  <-- R  <-- R  <-- R  <-- 0
                                  
     0      1      2      3      4

o6 : ChainComplex
(That was an expensive way of resolving M.)