Abstract
Given a dense additive subgroup G of \(\mathbb {R}\) containing \(\mathbb {Z}\), we consider its intersection \(\mathbb {G}\) with the interval [0, 1[ with the induced order and the group structure given by addition modulo 1. We axiomatize the theory of \(\mathbb {G}\) and show it is model-complete, using a Feferman-Vaught type argument. We show that any sufficiently saturated model decomposes into a product of a standard part and two ordered semigroups of infinitely small and infinitely large elements.
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Luc Bélair was partially supported by NSERC and the second author by FRS-FNRS.
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Bélair, L., Point, F. Fractional parts of dense additive subgroups of real numbers. Algebra Univers. 79, 92 (2018). https://doi.org/10.1007/s00012-018-0572-2
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DOI: https://doi.org/10.1007/s00012-018-0572-2