bio  website  sas.upenn.edu/~vnanda 

location  Philadelphia, PA  
age  
visits  member for  2 years, 11 months 
seen  1 hour ago  
stats  profile views  4,498 
Currently a postdoc at UPenn, was a graduate student at Rutgers. Author of the Perseus Morsetheoretic computational homology software.
21h

reviewed  Approve suggested edit on Failure of Fredholm property of elliptic PDE systems 
1d

comment 
Reference request: Book of topology from “Topos” point of view
Welcome to MO! $~~~$ 
Aug 29 
awarded  Popular Question 
Aug 26 
comment 
Brouwer fixed points via flow
PicardLindelof and its analogues only guarantee the existence of solutions locally. 
Aug 25 
reviewed  Approve suggested edit on What does the defect of a block measure? 
Aug 24 
reviewed  Reject suggested edit on Who named it the Snake Lemma? 
Aug 24 
reviewed  Approve suggested edit on Metric on the set of subsets of the rational primes 
Aug 21 
revised 
Are there “chain complexes” and “homology groups” taking values in pairs of topological spaces?
Removed old update. 
Aug 14 
comment 
Zigzags and contractibility of categories
@OmarAntolínCamarena Yes, sorry about that. And thanks for the helpful comments which brought the question to its present form. 
Aug 14 
comment 
In a fibration, can a deformation retraction of the base be lifted to the total space?
It seems as though the OP is asking precisely for those "mild conditions" that you've mentioned in your answer. 
Aug 14 
answered  Simplicial complices on unlabelled vertices 
Aug 14 
accepted  Zigzags and contractibility of categories 
Aug 14 
revised 
Zigzags and contractibility of categories
added 136 characters in body 
Aug 14 
revised 
Zigzags and contractibility of categories
modified in light of comments 
Aug 13 
comment 
Zigzags and contractibility of categories
Dear @Fedotov, I understand. So if the coherent nerve of the hammock localization has an initial element, can we then conclude that the original category is contractible as well? And does the localization functor induce a homotopy equivalence on classifying spaces in this case? 
Aug 13 
comment 
Zigzags and contractibility of categories
@ZhenLin certainly I don't mean to use this for anything like $\mathbf{Set}$. But tons of examples can be generated by taking various copies of $x \to x_0 \gets x_1 \cdots$ and gluing them all at $x$ for instance. The category so obtained does not have an initial object, but the zigzag category contracts to $x$. 
Aug 13 
asked  Zigzags and contractibility of categories 
Aug 11 
reviewed  Approve suggested edit on Convex hull of total orders 
Aug 11 
accepted  When is the determinant a Morse function? 
Aug 2 
comment 
Does every compact manifold exhibit an almost global chart
@MatthiasWendt It doesn't look like a smooth structure is being assumed on $M$. 