Some interesting birational morphisms of smooth affine quadric 3-folds

08/30/2022

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by   Cinzia Bisi, et al.

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We study a family of birational maps of smooth affine quadric 3-folds x_1x_4-x_2x_3= constant, over ℂ, which seems to have some (among many others) interesting/unexpected characters: a) they are cohomologically hyperbolic, b) their second dynamical degree is an algebraic number but not an algebraic integer, and c) the logarithmic growth of their periodic points is strictly smaller than their algebraic entropy. These maps are restrictions of a polynomial map on ℂ^4 preserving each of the quadrics. The study in this paper is a mixture of rigorous and experimental ones, where for the experimental study we rely on the Bertini which is a reliable and fast software for expensive numerical calculations in complex algebraic geometry.