Bochnak–Kucharz approximation conjecture for odd-dimensional real algebraic sets

From papers

Let nn be a positive odd integer, and let XX be a nonsingular compact connected real algebraic set of dimension nn. A regular map means a map given by regular functions on XX. Bochnak–Kucharz approximation conjecture. Every continuous map from XX to Sn\mathbb{S}^n is homotopic to a regular one.

The conjecture concerns approximation of continuous maps by algebraic maps. It is known to hold for n=1n=1, but the paper states that it is disproved for all n1(mod4)n\equiv 1\pmod 4 with n>1n>1; its status for the remaining odd dimensions is not settled here.

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Sources & referencesView supporting material

Primary source

Juliusz Banecki, “Invariants of real affine varieties based on their complexifications”, arXiv:2605.22941 (2026).

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