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foldComplex -- converts a chain complex into a differential module

Usage:

foldComplex(C)
Inputs:
- C, a complex,
- d, an integer,
Outputs:
- a differential module,

Description

Given a chain complex C and integer d it creates the corresponding (flag) differential module of degree d.

i1 : R = QQ[x,y];

i2 : C = freeResolution ideal(x,y)

      1      2      1
o2 = R  <-- R  <-- R
                    
     0      1      2

o2 : Complex

i3 : D = foldComplex(C,0);

i4 : D.dd_1

o4 = {0} | 0 x y 0  |
     {1} | 0 0 0 -y |
     {1} | 0 0 0 x  |
     {2} | 0 0 0 0  |

             4      4
o4 : Matrix R  <-- R

See also

differentialModule(Complex) -- converts a complex into a differential module
unfold -- converts a differential module into a 1-periodic complex
resDM -- uses a "killing cycles"-style construction to find a free resolution of a differential module
resMinFlag -- gives a minimal free flag resolution of a differential module of degree 0

Ways to use foldComplex:

foldComplex(Complex,ZZ)

For the programmer

The object foldComplex is a method function.

The source of this document is in MultigradedBGG.m2:731:0.