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math.AG2026

Invariants of real affine varieties based on their complexifications

Juliusz Banecki

We introduce a new family of invariants of real algebraic sets defined in terms of the topology of their complexifications and compute some of these invariants for spheres. This al…

math.AG2026

Optimal embedding dimension in the Nash--Tognoli theorem

Juliusz Banecki

We prove that every smooth compact submanifold of can be approximated up to a small isotopy by the real locus of a nonsingular complex algebraic subset of $\C^n$ defined ove…

math.AG2025

Uniform rationality of products with the plane

Juliusz Banecki

Let be a nonsingular rational variety. We prove that is uniformly rational. It follows that nonsingular stably rational varieties are stably uniformly ra…

math.AG2025

Homotopy properties of regular mappings into real retract rational varieties

Juliusz Banecki

We study homotopy properties of regular mappings from spheres into a real retract rational variety . We show that the homotopy classes which are represented by such mappings for…

math.AG2024

Extension of -regulous functions from varieties of arbitrary dimension

Juliusz Banecki

We prove that a -regulous function defined on a non-singular affine variety can always be extended to the entire affine space.

math.AG2024

Retract rational varieties are uniformly retract rational

Juliusz Banecki

We prove that nonsingular retract rational algebraic varieties over any infinite field are uniformly retract rational. As a consequence, every rational, projective, nonsingular com…