A map defined by one or more polynomials. Given a field , a polynomial map is a map such that for all points ,
for suitable polynomials . The zero set of is the set of all solutions of the simultaneous equations , and is an algebraic variety in .
An example of polynomial map is the th coordinate map , defined by for all . In the language of set theory, it is the projection of the Cartesian product onto the th factor.
Polynomial maps can be defined on any nonempty subset of . If is an affine variety, then the set of all polynomial maps from to is the coordinate ring of . If is an affine variety of , then every polynomial map induces a ring homomorphism , defined by . Conversely, every ring homomorphism determines a polynomial map , where .
A polynomial map is a real-valued polynomial function. Its graph is the plane algebraic curve with Cartesian equation .