ECCC-Report TR06-102https://eccc.weizmann.ac.il/report/2006/102Comments and Revisions published for TR06-102en-usFri, 25 Aug 2006 12:37:56 +0300
Paper TR06-102
| Dispersion of Mass and the Complexity of Randomized Geometric Algorithms |
Luis Rademacher,
Santosh Vempala
https://eccc.weizmann.ac.il/report/2006/102How much can randomness help computation? Motivated by this general question and by volume computation, one of the few instances where randomness provably helps, we analyze a notion of dispersion and connect it to asymptotic convex geometry. We obtain a nearly quadratic lower bound on the complexity of randomized volume algorithms for convex bodies in R^n (the current best algorithm has complexity roughly n^4, conjectured to be n^3). Our main tools, dispersion of random determinants and dispersion of the length of a random point from a convex body, are of independent interest and applicable more generally; in particular, the latter is closely related to the variance hypothesis from convex geometry. This geometric dispersion also leads to lower bounds for matrix problems and property testing.
Fri, 25 Aug 2006 12:37:56 +0300https://eccc.weizmann.ac.il/report/2006/102