Title
An exponential lower bound for homogeneous depth-5 circuits over finite fields
Abstract
In this paper, we show exponential lower bounds for the class of homogeneous depth-5 circuits over all small finite fields. More formally, we show that there is an explicit family {P-d} of polynomials in VNP, where P-d is of degree d in n = d(O(1)) variables, such that over all finite fields GF(q), any homogeneous depth-5 circuit which computes Pd must have size at least exp(Omega(q)(root d)). To the best of our knowledge, this is the first super-polynomial lower bound for this class for any non-binary field. Our proof builds up on the ideas developed on the way to proving lower bounds for homogeneous depth-4 circuits [Gupta et al., Fournier et al., Kayal et al., Kumar-Saraf] and for non-homogeneous depth-3 circuits over finite fields [Grigoriev-Karpinski, Grigoriev-Razborov]. Our key insight is to look at the space of shifted partial derivatives of a polynomial as a space of functions from GF(q)(n) to GF(q) as opposed to looking at them as a space of formal polynomials and builds over a tighter analysis of the lower bound of Kumar and Saraf [Kumar-Saraf].
Year
DOI
Venue
2015
10.4230/LIPIcs.CCC.2017.31
Leibniz International Proceedings in Informatics
Keywords
DocType
Volume
arithmetic circuits,lower bounds,separations,depth reduction
Journal
79
ISSN
Citations 
PageRank 
1868-8969
6
0.42
References 
Authors
15
2
Name
Order
Citations
PageRank
Mrinal Kumar 00011649.94
Ramprasad Saptharishi218413.72