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Revision of How to use the Bolzano-Weierstrass theorem from Sat, 24/01/2009 - 16:16

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The Bolzano-Weierstrass theorem asserts that every bounded sequence of real numbers has a convergent subsequence. More generally, it states that if X is a closed bounded subset of \mathbb{R}^n then every sequence in X has a subsequence that converges to a point in X. This article is not so much about the statement, or its proof, but about how to use it in applications. As we shall see, one of the signs to look out for is any statement that has the form "For every \delta>0 there exists a\in X such that P(a)," where X is some bounded set.

Example 1