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On the structure of semialgebraic sets over p-adic fields

Published online by Cambridge University Press:  12 March 2014

Philip Scowcroft
Affiliation:
Department of Mathematics, Yale University, New Haven, Connecticut 06520
Lou van den Dries*
Affiliation:
Department of Mathematics, Stanford University, Stanford, California 94305
*
Department of Mathematics, University of Illinois, Urbana, Illinois 61801

Extract

In his Singular points of complex hypersurfaces Milnor proves the following “curve selection lemma” [10, p. 25]:

Let VR m be a real algebraic set, and let UR m be an open set defined by finitely many polynomial inequalities:

Lemma 3.1. If UV contains points arbitrarily close to the origin (that is if 0 ∈ Closure (UV)) then there exists a real analytic curve

with p(0) = 0 and with p(t)UV for t > 0.

Of course, this result will also apply to semialgebraic sets (finite unions of sets UV), and by Tarski's theorem such sets are exactly the sets obtained from real varieties by means of the finite Boolean operations and the projection maps R n+1R n . If, in this tiny extension of Milnor's result, we replace ‘R’ everywhere by ‘Q p ’, we obtain a p-adic curve selection lemma, a version of which we will prove in this essay. Semialgebraic sets, in the p-adic context, may be defined just as they are over the reals: namely, as those sets obtained from p-adic varieties by means of the finite Boolean operations and the projection maps . Analytic maps are maps whose coordinate functions are given locally by convergent power series.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1988

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References

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