picardGroup f
Given a toric map $f : X \to Y$, this method returns the induced map of abelian groups from the Picard group of $Y$ to the Picard group of $X$. In other words, picardGroup is a contravariant functor on the category of normal toric varieties.
We illustrate this method on the projection from the first Hirzebruch surface to the projective line.
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The induced map between the Picard groups is compatible with the induced map between the groups of torus-invariant Cartier divisors.
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Neither the source nor the target of the toric map needs to be smooth.
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The source of this document is in /build/reproducible-path/macaulay2-1.25.05+ds/M2/Macaulay2/packages/NormalToricVarieties/ToricMapsDocumentation.m2:1331:0.