© 2000 by London Mathematical Society
© The London Mathematical Society
On Ritt's Factorization of Polynomials
Department of Pure Mathematics and Mathematical Statistics, Centre for Mathematical Sciences, University of Cambridge Wilberforce Road, Cambridge CB3 0WB, afb{at}dpmms.cam.ac.uk
Department of Pure Mathematics and Mathematical Statistics, Centre for Mathematical Sciences, University of Cambridge Wilberforce Road, Cambridge CB3 0WB, ntw{at}dpmms.cam.ac.uk
Received 10 February 1999. Revision received 18 August 1999.
Ritt has shown that any complex polynomial p can be written as the composition of polynomials p1,...,pm, where each pj is prime in the sense that it cannot be written as a non-trivial composition of polynomials. The factors pj are not unique but the number m of them is, as is the set of the degrees of the pj. The paper extends Ritt's theory and, in particular, a third invariant of the decomposition is introduced.