We study depth three arithmetic circuits with bounded top fanin. We give the first deterministic polynomial time blackbox identity test for depth three circuits with bounded top fanin over the field of rational numbers, thus resolving a question posed by Klivans and Spielman (STOC 2001).

Our main technical result is ... more >>>

A constant-depth circuit consists of AND and OR gates of unbounded fan-in, arranged in a constant number of layers, that read the input literals; for example, a depth-three circuit is an OR of CNFs or an AND of DNFs. The classical lower bound of Håstad (1989) states that every depth-$d$ ... more >>>