Hitting Sets For Regular Branching Programs
Speaker: TedTitle: Hitting Sets For Regular Branching Programs
Date: 23 Aug 2021 17:30-19:00 EST
Location: SEC Level 3 NW Terrace for dinner and 3.301 for talk
Food: Chinese
Abstract: A recent like of work (HZ FOCS ‘18, CDRST CCC ‘21, PV CCC ‘21, H RANDOM ‘21) has developed “error reduction” procedures that take a weak pseudorandom object (often a pseudorandom generator) and output a strong pseudorandom object with nearly no degradation in seed length. These works have focused on fooling general ordered branching programs (HZ, CDRST, H) or the weaker model of permutation branching programs (PV). The intermediate model of regular branching programs is strong enough to capture the problem of derandomizing space-bounded computation, but in the relevant parameter regimes, the best known weak pseudorandom object was Nisan’s PRG for general ordered branching programs from 1990. I will present a weak pseudorandom object for regular programs that breaks this barrier. The construction is based on results and ideas from (BRRY FOCS ‘10, HPV ITCS ‘21) and is extremely simple. I will also sketch how an error reduction result for the regular case would, combined with this result, lead to an improved derandomization of randomized logspace.