Re; Tally[ ] and Union[ ]
- To: mathgroup at smc.vnet.net
- Subject: [mg83398] Re; Tally[ ] and Union[ ]
- From: Thomas E Burton <tburton at brahea.com>
- Date: Mon, 19 Nov 2007 06:18:39 -0500 (EST)
I immediately suspected Combinatorica`IsomorphicQ. I was able to convince myself, however, that IsomorphicQ is symmetric and transitive over the set of 21 graphs produced by diagrams. Do we ask any more of a test for equivalence? If not, then suspicion reverts to Tally, which is yielding too many results. I've no answer. > "A sorted Tally is equivalent to a list of counts for the Union:" > > This is what I indeed expect of Tally and Union, in particular then > it holds for any list: Length[Tally[list]] is equal to Length > [Union[list]].