Title
A #SAT Algorithm for Small Constant-Depth Circuits with PTF gates
Abstract
We show that there is a better-than-brute-force algorithm that, when given a small constant-depth Boolean circuit C made up of gates that compute constant-degree Polynomial Threshold functions or PTFs (i.e., Boolean functions that compute signs of constant-degree polynomials), counts the number of satisfying assignments to C in significantly better than brute-force time. Formally, for any constants d, k, there is an $$\varepsilon > 0$$ such that the zero-error randomized algorithm counts the number of satisfying assignments to a given depth-d circuit C made up of k-PTF gates such that C has at most $$n^{1+\varepsilon }$$ many wires. The algorithm runs in time $$2^{n-n^{\Omega (\varepsilon )}}.$$ Before our result, no algorithm for beating brute-force search was known for counting the number of satisfying assignments even for a single degree-k PTF (which is a depth-1 circuit with linearly many wires).We give two different algorithms for the case of a single PTF. The first uses a learning algorithm for learning degree-1 PTFs (or Linear Threshold Functions) using comparison queries due to Kane, Lovett and Moran (STOC 2018), and the second uses a proof of Hofmeister (COCOON 1996) for converting a degree-1 PTF to a depth-two threshold circuit with small weights. We show that both these ideas fit nicely into a memoization approach that yields the #SAT algorithms.
Year
DOI
Venue
2018
10.1007/s00453-021-00915-7
Algorithmica
DocType
Volume
Issue
Journal
84
4
ISSN
Citations 
PageRank 
0178-4617
0
0.34
References 
Authors
11
5
Name
Order
Citations
PageRank
Swapnam Bajpai100.34
Vaibhav Krishan200.34
Deepanshu Kush301.35
Nutan Limaye413420.59
Srikanth Srinivasan523.75