Abstract
In this paper we show that two disjoint basic closed semialgebraic sets, defined over a real closed field R, can be separated by a polynomial, if one of them has dimension ≦2. Counterexamples are given in all higher dimensions.
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Bröcker, L. On the separation of basic semialgebraic sets by polynomials. Manuscripta Math 60, 497–508 (1988). https://doi.org/10.1007/BF01258667
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DOI: https://doi.org/10.1007/BF01258667