Commit 2020-12-07 10:37 44400c99
View on Github →feat(dynamics/circle/rotation_number): translation numbers define a group action up to a semiconjugacy (#5138)
Formalize a theorem by Étienne Ghys: given two lifts f₁, f₂ of
actions of a group G on the circle by orientation preserving
homeomorphisms to the real line, assume that for each g : G the
translation numbers of f₁ g and f₂ g are equal. Then the actions
are semiconjugate by a (possibly discontinuous) circle map.