Results 51 to 60 of about 7,542 (104)
A remark on the rank of finite
Comptes Rendus. Mathématique, 2020 In this note, we improve a result of Prokhorov and Shramov on the rank of finite p-subgroups of the group of birational transformations of a rationally connected variety. Known examples show that the bounds obtained are optimal in many cases.
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Log-uniruled affine varieties without cylinder-like open subsets
, 2012 A classical result of Miyanishi-Sugie and Keel-McKernan asserts that for smooth affine surfaces, affine-uniruledness is equivalent to affine-ruledness, both properties being in fact equivalent to the negativity of the logarithmic Kodaira dimension.
Dubouloz, Adrien, Kishimoto, Takashi
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Automorphism group of the moduli space of parabolic bundles over a curve
, 2019 We find the automorphism group of the moduli space of parabolic bundles on a smooth curve (with fixed determinant and system of weights). This group is generated by: automorphisms of the marked curve, tensoring with a line bundle, taking the dual, and ...
Alfaya, David, Gomez, Tomas L.
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Normal forms and Tyurin degenerations of K3 surfaces polarized by a rank 18 lattice
Mathematische Nachrichten, Volume 298, Issue 3, Page 806-828, March 2025.Abstract We study projective Type II degenerations of K3 surfaces polarized by a certain rank 18 lattice, where the central fiber consists of a pair of rational surfaces glued along a smooth elliptic curve. Given such a degeneration, one may construct other degenerations of the same kind by flopping curves on the central fiber, but the degenerations ...
Charles F. Doran +2 more
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On the group of automorphisms of a quasi-affine variety
, 2014 Let K be an algebraically closed field of characteristic zero.
Jelonek, Zbigniew
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Parameter Constraints and Real Structures in Quadratic Semicomplete Vector Fields on C3
International Journal of Mathematics and Mathematical Sciences, Volume 2025, Issue 1, 2025.It is a remarkable fact that among the known examples of quadratic semicomplete vector fields on C3, it is always possible to find linear coordinates where the corresponding vector field has all—or “almost all”—coefficients in the real numbers. Indeed, the coefficients are very often integral.
Daniel de la Rosa Gómez, Shikha Binwal
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Birational automorphisms of nodal quartic threefolds
, 2008 It is well-known that a nonsingular minimal cubic surface is birationally rigid; the group of its birational selfmaps is generated by biregular selfmaps and birational involutions such that all relations between the latter are implied by standard relations between reflections on an elliptic curve.
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On the primitivity of birational transformations of irreducible symplectic manifolds
, 2016 Let $f\colon X\dashrightarrow X$ be a bimeromorphic transformation of a complex irreducible symplectic manifold $X$. Some important dynamical properties of $f$ are encoded by the induced linear automorphism $f^*$ of $H^2(X,\mathbb Z)$. Our main result is
Bianco, Federico Lo
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Unboundedness for motivic invariants of birational automorphisms
We introduce horizontal and vertical motivic invariants of birational maps between rational dominant maps and study their basic properties. As a first application, we show that the (usual) motivic invariants vanish for birational automorphisms of threefolds over algebraically closed fields of characteristic zero.
Lin, Hsueh-Yung, Shinder, Evgeny
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