bio  website  math.rice.edu/~andyp 

location  Houston, TX  
age  35  
visits  member for  5 years, 1 month 
seen  10 hours ago  
stats  profile views  13,362 
associate professor at Rice University
2d

comment 
Counting Ribbon graphs
@Cusp: The data is redundant since $e = vd/2$. If you want isomorphism classes, this seems impossible (in the moral, not the technical sense) for the same reason that it is impossible to write down a closed formula for the number of isomorphism classes of degree $d$ graphs with $v$ vertices. 
Nov 23 
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Koebe–Andreev–Thurston theorem  where can I find a proof?
nb: As an illustration of the connection to conformal geometry, you can construct circle packing of the disc from any planar graph; the "exterior" circles are all tangent to the exterior circle. The different possible unit disc circle packings realizing a given planar graph then differ by Mobius transformations. 
Nov 23 
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Koebe–Andreev–Thurston theorem  where can I find a proof?
@AllenKnutson: I'm not familiar with the term "coin graphs", but the circle packing theorem as stated in the question is quite old (it basically goes back to Koebe, though it has been rediscovered several times). My guess is that this is simply a matter of two communities of people not talking to each other. The various proofs of the circle packing theorem that I know are not really combinatorial. As Thurston taught us, constructing a circle packing is very similar to constructing a conformal map, so it does not surprise me that the graph theory community has not managed to prove it. 
Nov 22 
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Koebe–Andreev–Thurston theorem  where can I find a proof?
A proof can be found in Stephenson's lovely book "Introduction to Circle Packing: The Theory of Discrete Analytic Functions". 
Nov 20 
awarded  Enlightened 
Nov 20 
awarded  Nice Answer 
Nov 16 
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Two (other) rings…are they isomorphic?
@WłodzimierzHolsztyński: While of course one can overdo this, I think that what the OP does here is totally fine, and I see no reason to criticize him for it (implicitly or otherwise). 
Nov 11 
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Synthetic vs. classical differential geometry
I think that most mainstream work in Riemannian geometry ignores SDG. Though I'm only on the boundary of Riemannian geometry, my impression is that there really isn't a "foundational crisis". The biggest issues are related to things where category theory is mostly pretty useless, like analysis. 
Nov 8 
awarded  Enlightened 
Nov 8 
awarded  Nice Answer 
Nov 8 
answered  Thurston geometries in dimension 4 
Oct 27 
awarded  Good Answer 
Oct 14 
awarded  Yearling 
Sep 30 
awarded  Explainer 
Sep 17 
awarded  Notable Question 
Aug 31 
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Top specialized journals
@BenoîtKloeckner : They have great ambitions, but I think that at this point they have not reached them (and who knows what will happen when they start charging authors to publish in them). 
Aug 25 
awarded  Enlightened 
Aug 25 
awarded  Nice Answer 
Aug 24 
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Second homology of mapping class group of genus 3
Thanks Kevin!!! 
Aug 24 
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Help with my research topic
While I am sorry you are having trouble, questions of the form "give me a thesis topic" are offtopic and I have voted to close. 