David A. McAllester Bart Selman Henry A. Kautz Evidence for Invariants in Local Search. 321-326 1997 conf/aaai/1997 AAAI/IAAI db/conf/aaai/aaai97.html#McAllesterSK97 http://www.aaai.org/Library/AAAI/1997/aaai97-050.php