New posts in Algebraic Groups

Action of symmetric matrices under $\mathrm{O}(n)$

Is $O_n({\bf Q})$ dense in $O_n({\bf R})$?

To describe an invariant trivector in dimension 8 geometrically

Bilinear forms in compact/semisimple Lie group theory

Which schemes are divisors of an abelian variety?

Relationship between fans and root data

Subgroup of $\mathrm{GL}_n$ stabilizing linear subspace skew-symmetric matrices

Is a representation of $\operatorname{SL}_n$ defined over a field $k$ if its image is contained in $\operatorname{GL}_n(k)$?

Absolutely irreducible representations of affine group schemes of finite type over a field

Sheafification of loop scheme/group