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Combinatorial properties of infinite sets. This is a corner-point of set theory and combinatorics.

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2 answers
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How decreasing can a bijection $f:\mathbb{N}\to\mathbb{N}$ be?

This is a follow-up to this question by Dominic van der Zypen. For each bijection $f:\mathbb{N}\to\mathbb{N}$, let $$\operatorname{rc}(f) := \liminf_{N\to\infty} \frac{\left|\left\{(m,n)\in\{1,\dots,N …
Saúl RM's user avatar
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