A Denjoy Type Theorem for Commuting Circle Diffeomorphisms with Derivatives Having Different Hölder Differentiability Classes
نویسندگان
چکیده
Let d > 2 be an integer number, and let fk, k ∈ {1, . . . , d}, be Ck commuting circle diffeomorphisms, with τk ∈ ]0, 1[ and τ1 + · · · + τd > 1. We prove that if the rotation numbers of the fk’s are independent over the rationals (that is, if the corresponding action of Z n on the circle is free), then they are simultaneously (topologically) conjugate to rotations. 2000 Math. Subj. Class. 22F05, 37C15, 37C80, 37E10.
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