LK is an implementation of the Lin-Kernighan heuristic for the Traveling  Salesman Problem and for the minimum weight perfect matching problem. It is  tuned for 2-d geometric instances, and has been applied to certain  instances with up to a million cities. Also included are instance generators  and Perl scripts for munging TSPLIB instances.<p>  This implementation introduces ``efficient cluster compensation'', an  experimental algorithmic technique intended to make the Lin-Kernighan  heuristic more robust in the face of clustered data.<p>  Parts of LK are rock solid. Other parts are alpha, and everything in between.  It's written in CWEB for your reading pleasure.