## Illinois Journal of Mathematics

### On circle endomorphisms

R. Cowen

#### Abstract

In [6], Shub and Sullivan posed the problem of finding complete measure theoretic invariants for analytic Lebesgue measure preserving expanding endomorphisms of $S^{1}$. In [2], the author gave necessary and sufficient conditions for two such endomorphisms to be isomorphic. These complete invariants were a mixture of a topological and measure-theoretic nature. Establishing them required finding a coboundary equation with no obvious method of construction. In this note we use a result by Arteaga to furnish a different set of complete isomorphism invariants, still of a mixed topological and measure-theoretic nature but far more easily checked than the ones established in [2].

#### Article information

Source
Illinois J. Math., Volume 44, Issue 3 (2000), 516-519.

Dates
First available in Project Euclid: 20 October 2009

Permanent link to this document
https://projecteuclid.org/euclid.ijm/1256060411

Digital Object Identifier
doi:10.1215/ijm/1256060411

Mathematical Reviews number (MathSciNet)
MR1772424

Zentralblatt MATH identifier
0967.37027

#### Citation

Cowen, R. On circle endomorphisms. Illinois J. Math. 44 (2000), no. 3, 516--519. doi:10.1215/ijm/1256060411. https://projecteuclid.org/euclid.ijm/1256060411