In this article we develop the theory of minors of non-commutative schemes. This study is motivated by applications in the theory of non-commutative resolutions of singularities of commutative schemes. In particular, we construct a categorical resolu
tion for non-commutative curves and in the rational case show that it can be realized as the derived category of a quasi-hereditary algebra.
The description of nilpotent Chernikov $p$-groups with elementary tops is reduced to the study of tuples of skew-symmetric bilinear forms over the residue field $mathbb{F}_p$. If $p e2$ and the bottom of the group only consists of $2$ quasi-cyclic su
mmands, a complete classification is given. We use the technique of quivers with relations.
We consider genera of polyhedra (finite cell complexes) in the stable homotopy category. Namely, the genus of a polyhedron X is the class of polyhedra Y such that all localizations of Y are stably isomorphic to the corresponding localizations of X. W
e prove that Y is in the genus of X if and only if the wedge XvB is stably isomorphic to YvB, where B is the wedge of all spheres S^n such that the n-th stable homotopy group of X is not torsion. We also prove that if XvX and XvY are stably isomorphic, so are also X and Y. Several examples of calculations of genera are considered.
