To mathematicians, X = Tree. The thing that cares what order the children are in is called a "planar tree" instead. Computer scientists don't know that things come in "unordered", so they dropped the word "planar" and just call the ordered things trees. --Michael On Thu, Jul 12, 2012 at 10:16 AM, Marc LeBrun <mlb@well.com> wrote:
="Mike Stay" <metaweta@gmail.com> Composition is associative, so I'd think you'd have a list rather than a tree. Can you expand a bit on what you're looking for?
I guess I'm seeking the "Official Name" for the tree data-structure analog that reflects the partitions vs. compositions distinction. Basically,
A Tree is either a Leaf or an ordered sequence of sub-Trees.
An X is either a Leaf or an unordered set of sub-X's.
What do you call an X?
="Gareth McCaughan" <gareth.mccaughan@pobox.com> "Unordered tree"?
That's reasonable, but I don't want to coin a new term if there's already an existing one--which I suspect there may be, though for some reason I can't seem to recall what it is.
As an "application", there's that nice categorical correspondence of 7-tuples of trees to trees, so what is the analog for X's--and so on.
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