On Sun, Jun 14, 2009 at 6:49 PM, Paul LaFollette<paul.lafolle...@gmail.com> wrote: > Now, suppose that I want to generate, say, the set of all ordered > trees with N nodes. I need to be able to represent the empty ordered > tree, i.e. the tree with with zero nodes. There are a lot of ways I > could do this. The problem is that I might tomorrow be looking > instead at rooted trees, or free trees, or Young tableaux and in each > case I will need to represent the empty rooted tree, or the empty free > tree, or the empty Young tableau. > > In a very real sense, the empty Young tableau IS a Young tableau and > the empty ordered tree IS an ordered tree. But in an equally real > sense they are the same "ghost of a thing" looked at in different > universes of discourse.
But do you also want the empty Young tableau to BE an ordered tree? A number? A diddlewoodaddy? It seems much more logical to me to define your Young tableaus such that the definition includes the empty one as well. -- André Engels, andreeng...@gmail.com -- http://mail.python.org/mailman/listinfo/python-list
