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Ilya Tyomkin

Publications and source records attributed to Ilya Tyomkin.

22 records · Page 2Linked to original sources
arXiv2008

On the quantum homology algebra of toric Fano manifolds

In this paper we study certain algebraic properties of the quantum homology algebra for the class of symplectic toric Fano manifolds. In particular, we examine the semi-simplicity of the quantum homology algebra, and the more general property of containing a field as a direct summand. Our main result provides an easily-verified sufficient condition for these properties which is independent of the symplectic form. Moreover, we answer two questions of Entov and Polterovich negatively by providing examples of toric Fano manifolds with non semi-simple quantum homology algebra, and others in which the Calabi quasi-morphism is non-unique.

math.SG↗
arXiv2006

On Severi varieties on Hirzebruch surfaces

In the current paper we prove that any Severi variety on a Hirzebruch surface contains a unique component parameterizing irreducible nodal curves of the given genus in characteristic zero.

math.AG↗
arXiv2001

Existence of Curves with Prescribed Topological Singularities

Throughout this paper we study the existence of irreducible curves C on smooth projective surfaces S with singular points of prescribed topological types S_1,...,S_r. There are necessary conditions for the existence of the type \sum_{i=1}^r μ(S_i) < aC^2+bC.K+c+1 for some fixed divisor K on S and suitable coefficients a, b and c, and the main sufficient condition that we find is of the same type, saying it is asymptotically optimal. Even for the case where S is the projective plane, ten years ago general results of this quality have not been known. An important ingredient for the proof is a vanishing theorem for invertible sheaves on the blown up S of the form O_{S'}(π^*D-\sum_{i=1}^r m_iE_i), deduced from the Kawamata-Vieweg Vanishing Theorem. Its proof covers the first part of the paper, while the middle part is devoted to the existence theorems. In the last part we investigate our conditions on ruled surfaces, products of elliptic curves, surfaces in projective 3-space, and K3-surfaces.

math.AG↗