Malcolm J. Beynon Investigating the Choice of l and u Values in the Extended Variable Precision Rough Sets Model. 61-68 2002 conf/rsctc/2002 Rough Sets and Current Trends in Computing http://link.springer.de/link/service/series/0558/bibs/2475/24750061.htm db/conf/rsctc/rsctc2002.html#Beynon02