The aim of this article is to define and study a notion unstable algebra over an operad that generalises the classical Steenrod algebra. For we focus on case characteristic 2. We $\star$-unstable $\mathcal P$-algebras, where P$ $\star$ commutative binary operation in P$. then build functor takes module $M$ free P$-algebra generated by $M$. Under some hypotheses $M$, identify as P$-algebra. Fina...

It is shown that the ghost kernel for certain equivariant stable cohomotopy groups of projective spaces is non-trivial. The proof is based on the Borel cohomology Adams spectral sequence and the calculations with the Steenrod algebra afforded by it.

We construct a generalization of the usual module of indecomposables for the mod 2 cohomology of a finite //-space. Structure theorems are obtained regarding how the Steenrod algebra acts on this module.

The periodic lambda algebra is a co-Koszul complex of the Steenrod algebra whose homology gives the E2 term for the Adams spectral sequence. Its elements are closely related to periodic homotopy theory, and exhibit periodic properties. In this paper we discuss an algorithm to compute the homology of the periodic lambda algebra, and investigate the algebraic structure for the E2 page of the vn p...