The goal of this paper is to present a modified version (GML) of ML invariant which should take into account rulings over a projective base and allow further stratification of smooth affine rational surfaces. We provide a non-trivial example where GML invariant is computed for a smooth affine rational surface admitting no C-actions. We apply GML invariant to computing ML invariant of some three...

Both boundary maps in K-theory are expressed in terms of surjections from projective C∗-algebras to semiprojective C∗-algebras. 1. Noncommutative Cells and Boundaries Cells are absolute retracts that tie together spheres of different dimensions. The analog of an absolute retract for a C-algebra is being projective. For better or worse, in the category of all C-algebras, we lose the projectivity...

Identifying PSL(2,C) as a projective group for patterns in the conformal camera model, the projective harmonic analysis on its double covering group SL(2,C) is presented in the noncompact and compact pictures–the pictures used to study different aspects of irreducible unitary representations of semisimple Lie groups. Bypassing technicalities of representation theory, but stressing the motivatio...

We generalize the well-known numerical criterion for projective spaces by Cho, Miyaoka and Shepherd-Barron to varieties with at worst quotient singularities. Let X be a normal projective variety of dimension n ≥ 3 with at most quotient singularities. Our result asserts that if C · (−KX) ≥ n + 1 for every curve C ⊂ X, then X ∼= P .

in this paper we show that if q is a power of a prime p , then the projective special linear group psl(2, q) and the stabilizer of a point of the projective line have maximum sum element orders among all proper subgroups of projective general linear group pgl(2, q) for q odd and even respectively

Let C: L L be a projective deformation of the second order of two totally pn focal pseudocongruences L and L of (m-l)-planes in projective spaces and n, 2m-i < n < 3m-l, and let K be a collineation realizing such a C. The deformation C is said to be weakly singular, singular, or a-strongly singular, s 3,4,..., if the collineation K gives projective deformations of order i, 2 or of all correspon...

Let C be a smooth projective curve over ℂ. n,d≥1.

For complex projective varieties, all natural transformations from constructible functions to homology (modulo torsion) are linear combinations of the MacPherson-Schwartz-Chern classes. In particular, the total Chern class is the only such natural transformation c such that for all projective spaces P, the top component of c(1P) is the fundamental class of P.

The following structure theorems are proved: An orbit of a real solvable Lie group in projective space that is a complex submanifold is isomorphic to C x (C*)m x Í2 , where Í2 is an open orbit of a real solvable Lie group in a projective rational variety. Also, any homogeneous space of a complex Lie group that is isomorphic to C" can be realized as an orbit in some projective space. As a conseq...

We study the ideals of the rational cohomology ring of the Hilbert scheme X [n] of n points on a smooth projective surface X . As an application, for a large class of smooth quasi-projective surfaces X , we show that every cup product structure constant of H∗(X ) is independent of n; moreover, we obtain two sets of ring generators for the cohomology ring H∗(X ). Similar results are established ...