Guest column: inapproximability results via Long Code based PCPs
SIGACT News Complexity Theory Column 47 Lane A. Hemaspaandra Dept. of Computer Science, University of Rochester Rochester, NY 14627, USA Introduction to Complexity Theory Column 47 Summer has come again. And what better way is there to spend a summer than to relax on a sandy beach, on a mountain top, or at a park s picnic tables, and. . . think theory! Summer is a particularly good time to attack the big questions whose openness just plain annoys you. In light of Reingold s L = SL result, does L-vs.-RL tempt you? If so, take it on! (But perhaps peek rst at Reingold Trevisan Vadhan s ECCC TR05-022.) Are you convinced that UP = NP should imply the collapse of the polynomial hierarchy? Make it so! (But if you hope to do so via showing that UP is contained in the low hierarchy, peek rst at Long Sheu s 1996 MST article.) You know that NP ©coNP ZPPNP and SNP ZPPNPNP , but believe that some of those s are = s or are S2 S2 2 (gasp!) provably strict containments (thus giving some insight into whether recent improvements (Cai in FOCS 2001; Cai et al. in Information and Computation 2005) in the collapses of the polynomial hierarchy from assumptions that NP is in P/poly, (NP © coNP)/poly, or coNP/poly are strict improvements)? Well, prove an = or nd evidence for a strict containment. . . or to really make this a summer for us all to remember, prove a strict containment! Wishing you happy theorems. Warmest thanks to Subhash for this month s guest column, Inapproximability Results via Long Code Based PCPs. Upcoming articles include John Hitchcock, Jack Lutz, and Elvira Mayordomo on The Fractal Geometry of Complexity Classes, Neil Immerman on Recent Progress in Descriptive Complexity, Piotr Faliszewski and me on Five Not-So-Easy Questions about the Semifeasible Sets, and Omer Reingold on a topic TBA. Guest Column: Inapproximability Results via Long Code based PCPs1 Subhash Khot2 Abstract This article gives an overview...