If the Module
M is graded then the module
N is a minimal presentation of
M. If not, then an attempt is made to improve the presentation of
M. An example follows.
R = ZZ/32003[a..d]; |
M = coker matrix {{a,1,b},{c,3,b+d}} |
N = minimalPresentation M |
peek N.cache |
g = N.cache.pruningMap |
g^-1 |
This function also works when M is
a graded module,
a chain complex, or
a coherent sheaf.
I = ideal(a^2,b^3,c^4,d^7) |
X = Proj R |
J = (module I)~ |
minimalPresentation J |