Sam Hopkins's user avatar
Sam Hopkins's user avatar
Sam Hopkins's user avatar
Sam Hopkins
  • Member for 11 years, 4 months
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99 votes
3 answers
5k views

Why do combinatorial abstractions of geometric objects behave so well?

39 votes
17 answers
8k views

Examples of "unsuccessful" theories with afterlives

34 votes
1 answer
3k views

Updates to Stanley's 1999 survey of positivity problems in algebraic combinatorics?

23 votes
1 answer
992 views

Why 'excedances' of permutations? [closed]

22 votes
3 answers
1k views

Cyclic action on Kreweras walks

21 votes
4 answers
3k views

Which fields have multiplicative group isomorphic to additive group times Z/2Z?

20 votes
2 answers
874 views

Counting problems where unlabeled is easier than labeled

20 votes
4 answers
2k views

Non-enumerative proof that, in average, less than 50% of tiles in domino tiling of 2-by-n rectangle are vertical?

19 votes
1 answer
2k views

Why did _Research in the Mathematical Sciences_ change from open access to subscription-based?

19 votes
2 answers
1k views

Is it possible that the GHKK canonical basis for cluster algebras is the Lusztig/Kashiwara dual canonical basis?

17 votes
0 answers
809 views

Is there a n/2 version of the Erdős-Hanani conjecture?

17 votes
3 answers
721 views

Matrices of combinatorial sequences that are inverse in two ways

16 votes
0 answers
323 views

Row of the character table of symmetric group with most negative entries

15 votes
5 answers
1k views

Longest increasing subsequence as measure of randomness

15 votes
2 answers
519 views

Is there a natural notion of completion of a Coxeter system?

15 votes
4 answers
687 views

Unified framework for posets with order polynomial product formulas

14 votes
2 answers
440 views

Ehrhart period collapse for $123\ldots k$-avoiding Birkhoff polytope?

14 votes
3 answers
671 views

Log-concavity of matroids: characterization of equality?

13 votes
2 answers
809 views

Cycle generating function of permutations with only odd cycles

13 votes
1 answer
522 views

Minuscule weights of parabolic sub-root systems are not far from dominant

13 votes
2 answers
711 views

Basis of coinvariant algebra on which reflection group acts as regular representation

13 votes
2 answers
1k views

Significance of half-sum of positive roots belonging to root lattice?

13 votes
1 answer
543 views

Bijective proof of recurrence for rooted unlabeled trees

12 votes
3 answers
892 views

Expected number of compositions needed to get constant function

12 votes
2 answers
488 views

Dynamics of RSK

12 votes
1 answer
592 views

Order polynomial of shifted double staircase

11 votes
1 answer
630 views

Two remarkable weighted sums over binary words

11 votes
6 answers
4k views

Non-constructive proofs vs. efficient algorithms

11 votes
1 answer
261 views

Infinite vertex-transitive graph where every automorphism has a fixed vertex

10 votes
1 answer
177 views

Reversals of autonomous subsets in right-angled Coxeter groups