Mark Wildon's user avatar
Mark Wildon's user avatar
Mark Wildon's user avatar
Mark Wildon
  • Member for 13 years, 8 months
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43 votes
2 answers
6k views

Alternating sum of square roots of binomial coefficients

23 votes
5 answers
2k views

Is there a short proof that the Kostka number $K_{\lambda \mu}$ is non-zero whenever $\lambda$ dominates $\mu$?

11 votes
1 answer
282 views

Permutation groups having a regular cyclic subgroup and a conjectured algebra of characters

10 votes
1 answer
295 views

Is there a bijective proof of an identity enumerating independent sets in cycles?

10 votes
1 answer
281 views

Rational even polynomials maximally tangent to the unit circle

9 votes
1 answer
820 views

Reference request: a locally cyclic group is isomorphic to a section of the rational numbers

9 votes
7 answers
723 views

Important combinatorial and algebraic interpretations of the coefficients in the polynomial $[n]!_q = (1+q)(1+q+q^2) \ldots (1+q+\cdots + q^{n-1})$

9 votes
2 answers
790 views

Regular elementary abelian subgroups of primitive permutation groups

8 votes
1 answer
209 views

Minimum number of permutations of $\{1,\ldots, n\}$ that together contain every $k$-subpermutation

8 votes
4 answers
974 views

Orbits of the projective special linear group on $\mathbf{Q} \cup \{\infty\}$

8 votes
2 answers
264 views

Is it possible for the reduction modulo $p$ of an non-commutative semisimple algebra to be commutative?

7 votes
3 answers
863 views

A balls and urns model for a hashing problem

7 votes
1 answer
436 views

Hopfian modules

6 votes
0 answers
298 views

Partitions of $\mathbb{F}_2^n$ related to perfect $1$-error correcting binary codes

6 votes
1 answer
406 views

Yoneda map for a composition of a representable functor and an arbitrary functor

5 votes
1 answer
169 views

A $q$-analogue of a characterization of polynomials by binomial coefficients

3 votes
0 answers
173 views

Differentiable functions on $\mathbb{R}^n$ whose derivative is everywhere a scalar multiple of a special orthogonal matrix

3 votes
2 answers
148 views

Breaking the rotate-then-substitute alphabetic cipher

2 votes
0 answers
76 views

Upper bound on decomposition numbers for the symmetric group in a block of weight $w$

2 votes
1 answer
298 views

When is there a subring of the complex numbers surjecting onto a given field of prime characteristic?