> The problem in my case is really one of scale. I have put a larger > example at the bottom of this message. When I try to find the > groebner basis in sage 4.1 (which seems to use polybori-0.5rc.p8) the > memory usage goes over 1.6GB and then sage crashes. It is possible > that it just isn't realistic to solve it using Groebner Bases. > However, I should say that when reformulated as a SAT solving problem, > the standard off the shelf minisat 2.0 code can solve it in 0.04 > seconds. This is despite the fact that minisat only takes CNF as the > input which means that all the structure of the problem has been > removed before it sees it.
Hi Raphael, note that Gröbner basis methods will always return a complete algebraic description of the solution set while SAT solving approaches terminate once *one* solution is found. Thus if there are many solutions they have an advantage. You can try to guess some variables in order to improve the efficiency of the Gröbner basis based methods. Cheers, Martin -- name: Martin Albrecht _pgp: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8EF0DC99 _otr: 47F43D1A 5D68C36F 468BAEBA 640E8856 D7951CCF _www: http://www.informatik.uni-bremen.de/~malb _jab: martinralbre...@jabber.ccc.de --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
