Given a (not necessarily finite) ring map $f:A \rightarrow{} B$ and a $B$-module $N$ which is finite over $A$, the function returns a presentation of $N$ as an $A$-module.
i1 : kk = QQ
o1 = QQ
o1 : Ring
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i2 : A = kk[t]
o2 = A
o2 : PolynomialRing
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i3 : B = kk[x,y]/(x*y)
o3 = B
o3 : QuotientRing
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i4 : use B
o4 = B
o4 : QuotientRing
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i5 : i = ideal(x)
o5 = ideal x
o5 : Ideal of B
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i6 : f = map(B,A,{x})
o6 = map(B,A,{x})
o6 : RingMap B <--- A
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i7 : pushFwd(f,module i)
1
o7 = A
o7 : A-module, free, degrees {1}
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