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PushForward > pushFwd(RingMap,Module)

pushFwd(RingMap,Module) -- push forward of a module via a finite ring map

Synopsis

Description

Given a (not necessarily finite) ring map $f : A \to B$, the $B$-module $M$ can be considered as a module over $A$. If $M$ is finite, this method returns the corresponding $A$-module.

i1 : kk = QQ;
i2 : A = kk[t];
i3 : B = kk[x,y]/(x*y);
i4 : use B;
i5 : i = ideal(x)

o5 = ideal x

o5 : Ideal of B
i6 : f = map(B,A,{x})

o6 = map (B, A, {x})

o6 : RingMap B <--- A
i7 : pushFwd(f,module i)

      1
o7 = A

o7 : A-module, free, degrees {1}

See also