darij grinberg's user avatar
darij grinberg's user avatar
darij grinberg's user avatar
darij grinberg
  • Member for 14 years, 3 months
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17 votes
2 answers
1k views

Constructive proof of a rational version of Perron-Frobenius?

15 votes
4 answers
1k views

Zero-sum partition of an abelian group

15 votes
3 answers
2k views

Hom(A,C) ⊗ Hom(B,D) injects into Hom(A⊗B,C⊗D): when? why?

15 votes
1 answer
2k views

Graded commutativity of cup in Hochschild cohomology

14 votes
3 answers
1k views

"Conjugacy rank" of two matrices over field extension

14 votes
2 answers
1k views

Hilbert 90 for algebras

14 votes
2 answers
2k views

Sym(V ⊕ ∧² V) isomorphic to direct sum of all Schur functors of V

14 votes
2 answers
2k views

Clifford PBW theorem for quadratic form

14 votes
1 answer
522 views

Is the discriminant of a free (as a module) $R$-algebra always congruent to a square modulo 4?

14 votes
3 answers
857 views

How few $k$-dimensional subspaces of $V$ are enough to have a complement to each $n-k$-dimensional subspace?

14 votes
1 answer
525 views

Have the "Bayreuther Mathematische Schriften" ever been digitalized?

13 votes
3 answers
988 views

Primitive elements of a tensor product of bialgebras

13 votes
2 answers
2k views

Diagonal invariants of the symmetric group on $k[X_1,X_2,...,X_n,Y_1,Y_2,...,Y_n]$

13 votes
2 answers
796 views

Gale-Shapley stable marriage theorem: can we entrust matchmaking to monkeys?

13 votes
1 answer
770 views

Noether-Deuring for injections and surjections?

13 votes
4 answers
2k views

Representations of Pin vs. Representations of Clifford

13 votes
2 answers
2k views

How ugly is the isomorphism R[GxH] = R[G] (X) R[H] for groups G, H?

12 votes
1 answer
6k views

Chinese Remainder Theorem for rings: why not for modules?

12 votes
5 answers
5k views

reduced ⊗ reduced = reduced; what about connected?

12 votes
1 answer
554 views

Factoring a polynomial into linear factors by ring extension

11 votes
3 answers
487 views

Local-globalism for similar matrices?

11 votes
3 answers
3k views

Gauss sum (with sign) through algebra

11 votes
1 answer
868 views

Connected graded involutive bialgebras (Hopf algebras) sought (for Dynkin idempotent checking)

11 votes
1 answer
1k views

PBW theorem over a Q-algebra, without freeness or flatness

11 votes
4 answers
1k views

Why is alpha-equivalence in untyped $\lambda$-calculus substitutive?

11 votes
1 answer
1k views

When are representation rings special lambda-rings? (variations of an old question)

11 votes
2 answers
829 views

How exactly does Schützenberger promotion relate to Striker-Williams promotion?

11 votes
1 answer
611 views

Plethysm of $\mathrm{QSym}$ into $\mathrm{QSym}$: can it be defined?

10 votes
3 answers
999 views

Arithmetic product of symmetric functions: why is it integral?

10 votes
1 answer
673 views

Analogues of the Knuth and Forgotten equivalences on permutations: have they been studied?