Lane A. Hemaspaandra Mitsunori Ogihara Gerd Wechsung Reducing the Number of Solutions of NP Functions. 394-404 http://link.springer.de/link/service/series/0558/bibs/1893/18930394.htm 2000 conf/mfcs/2000 MFCS db/conf/mfcs/mfcs2000.html#HemaspaandraOW00