2011-11-13 huffman 2011-11-13 remove unnecessary number-representation-specific rules from metis calls; speed up another proof
2011-09-06 huffman 2011-09-06 avoid using legacy theorem names
2011-01-13 wenzelm 2011-01-13 eliminated global prems; tuned proofs;
2010-11-28 nipkow 2010-11-28 gave more standard finite set rules simp and intro attribute
2010-08-06 wenzelm 2010-08-06 modernized specifications; tuned headers;
2010-03-03 krauss 2010-03-03 fix fragile proof using old induction rule (cf. bdf8ad377877)
2009-09-01 haftmann 2009-09-01 some reorganization of number theory