Let and be piecewise smooth circle homeomorphisms with break points and identical irrational rotation numbers. We provide one sufficient and necessary condition for the absolute continuity of conjugation map between and .
"On Absolute Continuity of Conjugations between Circle Maps with Break Points." Abstr. Appl. Anal. 2012 (SI15) 1 - 12, 2012. https://doi.org/10.1155/2012/134701