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Topic: This Week's Finds in Mathematical Physics (Week 236)
Replies: 29   Last Post: Aug 24, 2006 9:00 AM

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david.corfield@tuebingen.mpg.de

Posts: 5
Registered: 3/14/06
Re: This Week's Finds in Mathematical Physics (Week 236)
Posted: Jul 30, 2006 12:01 PM
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> Maybe you meant Motzkin *trees*.

No, I did mean paths:

"A001006 Motzkin numbers: number of ways of drawing any number of
nonintersecting chords among n points on a circle.

Also number of Motzkin n-paths: paths from (0,0) to (n,0) in an n X n
grid using only steps U = (1,1), F = (1,0) and D = (1,-1)."

http://www.research.att.com/~njas/sequences/A001006

But of course there are loads of combinatorial interpretations,
including the trees you mention (which was actually the way I found the
link between Leinster and Fiore's construction and the Motzkin
numbers.)

> If anyone who knows categories, combinatorics and Galois theory
> wants to become a math grad student at UCR and work on the project
> Jeff and I dropped, they should contact me.


Now, that's an excellent offer.



Date Subject Author
7/26/06
Read This Week's Finds in Mathematical Physics (Week 236)
baez@math.removethis.ucr.andthis.edu
7/27/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
david.corfield@tuebingen.mpg.de
7/29/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
baez@math.removethis.ucr.andthis.edu
7/30/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
david.corfield@tuebingen.mpg.de
8/1/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
john baez
7/28/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
Jim Heckman
7/29/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
baez@math.removethis.ucr.andthis.edu
7/31/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
Jim Heckman
8/1/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
Tom Leinster
8/2/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
john baez
7/28/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
tchow@lsa.umich.edu
7/29/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
baez@math.removethis.ucr.andthis.edu
7/30/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
tchow@lsa.umich.edu
8/2/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
john baez
8/7/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
Keith Ramsay
8/8/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
john baez
8/8/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
tchow@lsa.umich.edu
8/24/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
Nik Weaver
7/28/06
Read Re: Order-preserving embeddings of ordinals in the real numbers
David Madore
7/28/06
Read Re: Order-preserving embeddings of ordinals in the real numbers
G. A. Edgar
7/29/06
Read Re: Order-preserving embeddings of ordinals in the real numbers
baez@math.removethis.ucr.andthis.edu
7/30/06
Read graphical representation of epsilon_0 (was: Re: Order-preserving embeddings of ordinals in the real numbers)
David Madore
8/1/06
Read Pictures of infinity
baez@math.removethis.ucr.andthis.edu
8/2/06
Read Re: Pictures of infinity
tony@mantis.co.uk
8/2/06
Read Re: Pictures of infinity
Alec Edgington
8/3/06
Read Re: Pictures of infinity
Dave L. Renfro
7/28/06
Read Re: Order-preserving embeddings of ordinals in the real numbers
Ian A. Mason
7/28/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
Kevin Buzzard
7/29/06
Read Re: This Week's Finds in Mathematical Physics (Week 236)
baez@math.removethis.ucr.andthis.edu

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