next | previous | forward | backward | up | top | index | toc | Macaulay2 web site
Macaulay2Doc :: ChainComplex ^ ZZ

ChainComplex ^ ZZ -- access member, cohomological degree

Synopsis

Description

Subscripts refer to homological degree, and superscripts refer to cohomological degree. It is only a matter of notation: C_(-n) is always the same as C^n.
i1 : R = QQ[x,y,z];
i2 : C = res coker vars R

      1      3      3      1
o2 = R  <-- R  <-- R  <-- R  <-- 0
                                  
     0      1      2      3      4

o2 : ChainComplex
i3 : C = dual C

      1      3      3      1
o3 = R  <-- R  <-- R  <-- R
                           
     -3     -2     -1     0

o3 : ChainComplex
i4 : C^2

      3
o4 = R

o4 : R-module, free, degrees {3:-2}
i5 : C^2 == C_(-2)

o5 = true

See also