LOWER BOUND ON WEIGHTS OF LARGE DEGREE THRESHOLD FUNCTIONS

An integer polynomial p of n variables is called a threshold gate for a Boolean function f of n variables if for all x is an element of {0, 1}(n) f(x) = 1 if and only if p(x) >= 0. The weight of a threshold gate is the sum of its absolute values. In this paper we study how large a weight might be needed if we fix some function and some threshold degree. We prove 2(ohm(22n/5)) lower bound on this value. The best previous bound was 2(ohm(2n/8)) (Podolskii, 2009). In addition we present substantially simpler proof of the weaker 2(ohm(2n/4)) lower bound. This proof is conceptually similar to other proofs of the bounds on weights of nonlinear threshold gates, but avoids a, lot of technical details arising in other proofs. We hope that this proof will help to show the ideas behind the construction used to prove these lower bounds.