The search complexity classes {\bf PPA} and {\bf PPAD} were proposed by Papadimitriou twenty years ago for characterizing the computational difficulties of many interesting natural search problems. While many members in the complete class of {\bf PPAD}, {\bf PPAD}-completeness, are established in the past twenty years, the understanding of the ... more >>>

We explicitly construct an extractor for two independent sources on $n$ bits, each with min-entropy at least $\log^C n$ for a large enough constant $C$. Our extractor outputs one bit and has error $n^{-\Omega(1)}$. The best previous extractor, by Bourgain [B2], required each source to have min-entropy $.499n$.

A key ... more >>>

We continue the study of the shifted partial derivative measure, introduced by Kayal (ECCC 2012), which has been used to prove many strong depth-4 circuit lower bounds starting from the work of Kayal, and that of Gupta et al. (CCC 2013).

We show a strong lower bound on the dimension ... more >>>