This function computes the homology algebra of the DGAlgebra A and determines if the multiplication on H(A) is trivial.
i1 : R = ZZ/101[a,b,c,d]/ideal{a^4,b^4,c^4,d^4}
o1 = R
o1 : QuotientRing
|
i2 : S = R/ideal{a^3*b^3*c^3*d^3}
o2 = S
o2 : QuotientRing
|
i3 : A = acyclicClosure(R,EndDegree=>3)
o3 = {Ring => R }
Underlying algebra => R[T ..T ]
1 8
3 3 3 3
Differential => {a, b, c, d, a T , b T , c T , d T }
1 2 3 4
o3 : DGAlgebra
|
i4 : B = A ** S
o4 = {Ring => S }
Underlying algebra => S[T ..T ]
1 8
3 3 3 3
Differential => {a, b, c, d, a T , b T , c T , d T }
1 2 3 4
o4 : DGAlgebra
|
i5 : isHomologyAlgebraTrivial(B,GenDegreeLimit=>6) o5 = true |
The command returns true since R --> S is Golod. Notice we also used the option GenDegreeLimit here.
i6 : R = ZZ/101[a,b,c,d]/ideal{a^4,b^4,c^4,d^4}
o6 = R
o6 : QuotientRing
|
i7 : A = koszulComplexDGA(R)
o7 = {Ring => R }
Underlying algebra => R[T ..T ]
1 4
Differential => {a, b, c, d}
o7 : DGAlgebra
|
i8 : isHomologyAlgebraTrivial(A) o8 = false |
The command returns false, since R is Gorenstein, and so HA has Poincare Duality, hence the multiplication is far from trivial.
The object isHomologyAlgebraTrivial is a method function with options.