Mark Redford Joseph Sawicki Prasad Subramaniam Cliff Hou Yervant Zorian Kimon Michaels DFM: don't care or competitive weapon? 296-297 2009 DAC http://doi.acm.org/10.1145/1629911.1629991 conf/dac/2009 db/conf/dac/dac2009.html#RedfordSSHZM09