This algorithm is based upon the methods described in the book of Evans and Griffith (Syzygies. London Mathematical Society Lecture Note Series, 106. Cambridge University Press, Cambridge, 1985.)
i1 : kk=ZZ/32003 o1 = kk o1 : QuotientRing |
i2 : S=kk[a..d] o2 = S o2 : PolynomialRing |
i3 : F=res (ideal vars S)^2
1 10 20 15 4
o3 = S <-- S <-- S <-- S <-- S <-- 0
0 1 2 3 4 5
o3 : ChainComplex
|
NOTE: We are viewing a syzygy module as a cokernel of an appropriate map.
i4 : isSyzygy(coker F.dd_3,3) -- the cokernel defined by the 3rd map is not a 3rd syzygy o4 = false |
i5 : isSyzygy(coker F.dd_4,3) -- the cokernel defined by the 4th map is a 3rd syzygy o5 = true |
This function is called within evansGriffith.
The object isSyzygy is a method function.