Applying techniques similar to Combinatorial Nullstellensatz we prove a lower estimate of |f(A,B)| for finite subsets A, B of a field, and a polynomial f(x,y) of the form f(x,y) = g(x) + yh(x), where the degree of g is greater than that of h.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-aa165-3-6, author = {Fedor Petrov}, title = {Combinatorial Nullstellensatz approach to polynomial expansion}, journal = {Acta Arithmetica}, volume = {166}, year = {2014}, pages = {279-282}, zbl = {1328.12003}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-aa165-3-6} }
Fedor Petrov. Combinatorial Nullstellensatz approach to polynomial expansion. Acta Arithmetica, Tome 166 (2014) pp. 279-282. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-aa165-3-6/