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Moscow Mathematical Journal

Volume 21, Issue 3, July–September 2021  pp. 593–612.

On deformations of hyperbolic varieties

Authors:  Mario Kummer (1) and Eli Shamovich (2)
Author institution:(1) Technische Universität Dresden, Fakultät Mathematik, Institut fü Geometrie, Zellescher Weg 12-14, 01062 Dresden, Germany
(2) Department of Mathematics, Ben-Gurion University of the Negev, Beer-Sheva, Israel


In this paper we study flat deformations of real subschemes of $\mathbb{P}^n$, hyperbolic with respect to a fixed linear subspace, i.e., admitting a finite surjective and real fibered linear projection. We show that the subset of the corresponding Hilbert scheme consisting of such subschemes is closed and connected in the classical topology. Every smooth variety in this set lies in the interior of this set. Furthermore, we provide sufficient conditions for a hyperbolic subscheme to admit a flat deformation to a smooth hyperbolic subscheme. This leads to new examples of smooth hyperbolic varieties.

2020 Math. Subj. Class. Primary: 14P99; Secondary: 14D99.

Keywords: Hyperbolic variety, Hilbert scheme, deformations.

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