English

Nonrigidity for circle homeomorphisms with several break points

Dynamical Systems 2019-01-15 v1

Abstract

Let ff and gg be two class PP-homeomorphisms of the circle S1S^{1} with break points singularities. Assume that the derivatives Df\textrm{Df} and Dg\textrm{Dg} are absolutely continuous on every continuity interval of Df\textrm{Df} and Dg\textrm{Dg} respectively. Denote by C(f)C(f) the set of break points of ff. For cS1c\in S^{1}, denote by πs,Of(c)(f)\pi_{s, O_{f}(c)}(f) the product of ff- jumps in break points lying to the ff- orbit of cc and by SO(f)={Of(c): cC(f) and πs,Of(c)(f)1}\textrm{SO}(f) = \{O_{f}(c):~c \in C(f)~\textrm{and}~\pi_{s, O_{f}(c)}(f)\neq 1\}, called the set of singular ff-orbits. The maps ff and gg are called break-equivalent if there exists a topological conjugating hh such that h(SO(f))=SO(g)  and  πs,Og(h(c))(g)=πs,Of(c)(f)  for all  cSO(f)h(\textrm{SO}(f))=\textrm{SO}(g)~~ \textrm{and} ~~ \pi_{s, O_{g}(h(c))}(g) = \pi_{s, O_{f}(c)}(f) ~~ \textrm{for all}~~ c\in \textrm{SO}(f). Assume that ff and gg have the same irrational rotation number of bounded type. We prove that if ff and gg are not break-equivalent, then any topological conjugating hh between ff and gg is a singular function i.e. it is a continuous on S1S^{1}, but Dh(x)=0\textrm{Dh}(x)=0 a.e. with respect to the Lebesgue measure. As a consequence if for some point dSO(f)d\in \textrm{SO}(f), πs,Og(d)(g){πs,Of(c)(f):cC(f)}\pi_{s, O_{g}(d)}(g)\notin \{\pi_{s, O_{f}(c)}(f): c\in C(f)\}, then the homeomorphism conjugation hh is a singular function. This later result generalizes previous results for one and two break points obtained by Dzhalilov-Akin-Temir and Akhadkulov-Dzhalilov-Noorani. Moreover, if ff and gg do not have the same number of singular orbits then the homeomorphism conjugating ff to gg is a singular function.

Keywords

Cite

@article{arxiv.1512.03327,
  title  = {Nonrigidity for circle homeomorphisms with several break points},
  author = {Abdelhamid Adouani and Habib Marzougui},
  journal= {arXiv preprint arXiv:1512.03327},
  year   = {2019}
}

Comments

32 pages

R2 v1 2026-06-22T12:06:30.376Z