1,212 research outputs found

    On the group of automorphisms of a quasi-affine variety

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    Let K be an algebraically closed field of characteristic zero. We show that if the automorphisms group of a quasi-affine variety X is infinite, then X is uniruled

    The Thom Conjecture for proper polynomial mappings

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    Let f,g:XYf,g:X \to Y be continuous mappings. We say that ff is topologically equivalent to gg if there exist homeomorphisms Φ:XX\Phi : X\to X and Ψ:YY\Psi: Y\to Y such that ΨfΦ=g.\Psi\circ f\circ \Phi=g. Let X,YX,Y be complex smooth irreducible affine varieties. We show that every algebraic family F:M×X(m,x)F(m,x)=fm(x)YF: M\times X\ni (m, x)\mapsto F(m, x)=f_m(x)\in Y of polynomial mappings contains only a finite number of topologically non-equivalent proper mappings. In particular there are only a finite number of topologically non-equivalent proper polynomial mappings f:CnCmf: \Bbb C^n\to\Bbb C^m of bounded (algebraic) degree. This gives a positive answer to the Thom Conjecture in the case of proper polynomial mappings

    Bi-Hermitian gray surfaces II

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    The aim of this paper is to classify bi-Hermitian compact surfaces (M,g)(M,g) whose Ricci tensor ρ\rho satisfies the relation Xρ(X,X)=13Xτg(X,X)\nabla_X\rho(X,X) =\frac13X\tau g(X,X).Comment: 17 page

    On smooth hypersurfaces containing a given subvariety

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    We reprove some results about affine complete intersections
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