Template:Analogous fixed-point theorems

From Wikipedia, the free encyclopedia

There are several fixed-point theorems which come in three equivalent variants: an algebraic topology variant, a combinatorial variant and a set-covering variant. Each variant can be proved separately using totally different arguments, but each variant can also be reduced to the other variants in its row. Additionally, each result in the top row can be deduced from the one below it in the same column.[1]

Algebraic topology Combinatorics Set covering
Brouwer fixed-point theorem Sperner's lemma Knaster–Kuratowski–Mazurkiewicz lemma
Borsuk–Ulam theorem Tucker's lemma Lusternik–Schnirelmann theorem
  1. ^ Nyman, Kathryn L.; Su, Francis Edward (2013), "A Borsuk–Ulam equivalent that directly implies Sperner's lemma", The American Mathematical Monthly, 120 (4): 346–354, doi:10.4169/amer.math.monthly.120.04.346, JSTOR 10.4169/amer.math.monthly.120.04.346, MR 3035127