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arXiv · 1803.00312

Monotone subsequence via ultrapower

Piotr Blaszczyk·Vladimir Kanovei·Mikhail G. Katz·Tahl Nowik
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Abstract

An ultraproduct can be a helpful organizing principle in presenting solutions of problems at many levels, as argued by Terence Tao. We apply it here to the solution of a calculus problem: every infinite sequence has a monotone infinite subsequence, and give other applications. Keywords: ordered structures; monotone subsequence; ultrapower; saturation; compactness

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Piotr Blaszczyk, Vladimir Kanovei, Mikhail G. Katz, Tahl Nowik. 2018-03-01. Monotone subsequence via ultrapower. https://doi.org/10.1515/math-2018-0015

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