Abhay Vardhan Koushik Sen Mahesh Viswanathan Gul Agha Actively Learning to Verify Safety for FIFO Automata. 494-505 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3328&spage=494 2004 conf/fsttcs/2004 FSTTCS db/conf/fsttcs/fsttcs2004.html#VardhanSVA04