title: Isochrons and phaseless sets.
abstract: Winfree has developed mathematical models for his phase resetting experiments on biological clocks. These models lead him to ask a number of mathematical questions concerning dynamical systems. This paper deals with these mathematical questions. In Winfree's terminology we show the existence of isochrons and establish some of their properties.
authors.affiliation: Division of Natural Sciences, University of California, 95064, Santa Cruz, CA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Guckenheimer