"Source: Text/Algebra/AlgBas.text";
"Line: 4170";
"Date: Fri Sep 26 12:10:11 2025";
"Main: Fri Sep 26 14:29:19 2025";
// original file: Text/Algebra/AlgBas.text, line: 4170
// Example: H94E26 ()
print "Example: H94E26";
ei := GetEchoInput();
SetEchoInput(true);
A := BasicAlgebra(CyclicGroup(4));
k := SimpleModule(A,1);
P := ProjectiveResolution(k,5);
R := CohomologyRing(k,5);
S<x,y> := CohomologyRingQuotient(R);
xi := CohomologyToChainmap(x,R,P);
x*x;
assert $1 eq 0;
IsZero(xi*xi);
assert not $1;
ModuleMaps(xi*xi);
H := NullHomotopy(xi*xi); 
ModuleMaps(H);
IsNullHomotopy(xi*xi,H);
assert $1;
SetEchoInput(ei);
