A family of four-variable expanders with quadratic growth
Mehdi Makhul
所有作者
Mehdi Makhul
文献摘要
We prove that if g(x,y) is a polynomial of constant degree d that
y2−y1 does not divide g(x1,y1)−g(x2,y2), then for any finite set $A
\subset R$ ∣X∣≫d∣A∣2,whereX:={b2−b1g(a1,b1)−g(a2,b2):a1,a2,b1,b2∈A}. We will see this bound is also tight for some polynomial g(x,y).