English

Classification of the spaces $C_p^*(X)$ within the Borel-Wadge hierarchy for a projective space $X$

Functional Analysis 2015-10-08 v1 Logic

Abstract

We study the complexity of the space Cp(X)C^*_p(X) of bounded continuous functions with the topology of pointwise convergence. We are allowed to use descriptive set theoretical methods, since for a separable metrizable space XX, the measurable space of Borel sets in Cp(X)C^*_p(X) (and also in the space Cp(X)C_p(X) of all continuous functions) is known to be isomorphic to a subspace of a standard Borel space. It was proved by A. Andretta and A. Marcone that if XX is a σ\sigma-compact metrizable space, then the measurable spaces Cp(X)C_p(X) and Cp(X)C^*_p(X) are standard Borel and if XX is a metrizable analytic space which is not σ\sigma-compact then the spaces of continuous functions are Borel-Π11\Pi^1_1-complete. They also determined under the assumption of projective determinacy (PD) the complexity of Cp(X)C_p(X) for any projective space XX and asked whether a similar result holds for Cp(X)C^*_p(X). We provide a positive answer, i.e. assuming PD we prove, that if n2n \geq 2 and if XX is a separable metrizable space which is in Σn1\Sigma^1_n but not in Σn11\Sigma^1_{n-1} then the measurable space Cp(X)C^*_p(X) is Borel-Πn1\Pi^1_n-complete. This completes under the assumption of PD the classification of Borel-Wadge complexity of Cp(X)C^*_p(X) for XX projective.

Keywords

Cite

@article{arxiv.1409.3840,
  title  = {Classification of the spaces $C_p^*(X)$ within the Borel-Wadge hierarchy for a projective space $X$},
  author = {Martin Doležal and Benjamin Vejnar},
  journal= {arXiv preprint arXiv:1409.3840},
  year   = {2015}
}