We establish a weak form of Carlson’s conjecture on the depth of the mod-p cohomology ring of a p-group. In particular, Duflot’s lower bound for the depth is tight if and only if the cohomology ring is not detected on a certain family of subgroups. The proofs use the structure of the cohomology ring as a comodule over the cohomology of the centre via the multiplication map. We demonstrate the e...

Starting from any operad P, one can consider on hand the free and other Baez–Dolan construction P. These two new operads have same space of operations, but with very different notions arity substitution. The main result this paper is that incidence bialgebras two-sided bar constructions constitute together a comodule bialgebra. objective: it concerns comodule-bialgebra structures groupoid slice...

We generalise recent results of M. Hovey and N. Strickland on comodule categories for Landweber exact algebras using the formalism of algebraic stacks.

Let A be a commutative comodule algebra over a commutative bialgebra H . The group of invertible relative Hopf modules maps to the Picard group of A, and the kernel is described as a quotient group of the group of invertible grouplike elements of the coring A⊗H , or as a Harrison cohomology group. Our methods are based on elementary K-theory. The Hilbert 90 Theorem follows as a corollary. The p...

We construct a Hom-bialgebra M(2) representing the functor of 2 × 2-matrices on Hom-associative algebras. We also construct a Hom-algebra analogue of the affine plane and show that it is a comodule Hom-algebra over M(2) in a suitable sense.

Let R be a commutative ring with multiplicative identity and C coassociative counital R-coalgebra the α-condition. A clean comodules defined based on cleanness rings modules. C-comodule M is comodule if endomorphism of clean. over itself i.e., as For an idempotent e ∈ R, there are relations between eRe R. It’s motivated us to investigate this condition for coalgebra. any C, we can construct ⇀C↼...

We construct an equivalence between the categories of vertex operator algebras and vertex operator coalgebras. We then investigate to what degree weak modules, generalized modules and ordinary modules carry corresponding comodule structures, as well as when various comodules carry module structure.