Sanjeev Mahajan Edgar A. Ramos K. V. Subrahmanyam Solving Some Discrepancy Problems in NC. 22-36 http://link.springer.de/link/service/series/0558/bibs/1346/13460022.htm 1997 conf/fsttcs/1997 FSTTCS db/conf/fsttcs/fsttcs97.html#MahajanRS97