The Journal of Symbolic Logic

Research Article

Decomposing Baire functions

J. Cichońa1, M. Moraynea1, J. Pawlikowskia1 and S. Soleckia1 c1

a1 Mathematical Institute, University of Wroclaw, 50–384 Wrocław, Poland


We discuss in the paper the following problem: Given a function in a given Baire class, into “how many” (in terms of cardinal numbers) functions of lower classes can it be decomposed? The decomposition is understood here in the sense of the set-theoretical union.

(Received April 30 1990)

(Revised December 19 1990)

Key words and phrases

  • Baire function;
  • Baire class;
  • Borel set;
  • cardinal number;
  • Baire space


c1 Department of Mathematics, University of California, Davis, California 95616-8633.