English

Feedback computability on Cantor space

Logic 2023-06-22 v5 Logic in Computer Science

Abstract

We introduce the notion of feedback computable functions from 2ω2^\omega to 2ω2^\omega, extending feedback Turing computation in analogy with the standard notion of computability for functions from 2ω2^\omega to 2ω2^\omega. We then show that the feedback computable functions are precisely the effectively Borel functions. With this as motivation we define the notion of a feedback computable function on a structure, independent of any coding of the structure as a real. We show that this notion is absolute, and as an example characterize those functions that are computable from a Gandy ordinal with some finite subset distinguished.

Keywords

Cite

@article{arxiv.1708.01139,
  title  = {Feedback computability on Cantor space},
  author = {Nathanael L. Ackerman and Cameron E. Freer and Robert S. Lubarsky},
  journal= {arXiv preprint arXiv:1708.01139},
  year   = {2023}
}
R2 v1 2026-06-22T21:05:43.175Z