2004/09/30 by Michael Eisermann · 1 citation
Mathematics · #math.QA #math.GT #msc:17B37 #msc:18D10 #msc:20F36 #msc:20G42 #msc:57M25
paper · pdf · doi:10.2140/agt.2005.5.537
published as Algebr. Geom. Topol. 5 (2005) 537-562 · Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol5/agt-5-23.abs.html
arxiv created 2005/06/30 · arxiv updated 2014/09/30
Given a rack Q and a ring A, one can construct a Yang-Baxter operator cQ: V tensor V --> V tensor V on the free A-module V = AQ by setting cQ(x tensor y) = y tensor xy for all x,y in Q. In answer to a question initiated by D.N. Yetter and P.J. Freyd, this article classifies formal deformations of cQ in the space of Yang-Baxter operators. For the trivial rack, where xy = x for all x,y, one has, of course, the classical setting of r-matrices and quantum groups. In the general case we introduce and calculate the cohomology theory that classifies infinitesimal deformations of cQ. In many cases this allows us to conclude that cQ is rigid. In the remaining cases, where infinitesimal deformations are possible, we show that higher-order obstructions are the same as in the quantum case.