Computability of Polish spaces up to homeomorphism

• Main Authors: Harrison-Trainor, Matthew, Melnikov, Alexander, Ng, Keng Meng
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2022
• Subjects: Science::Mathematics; Computer Analysis; Applications of Computable Structure Theory
• Online Access: https://hdl.handle.net/10356/159280
• Institution: Nanyang Technological University

We study computable Polish spaces and Polish groups up to homeomorphism. We prove a natural effective analogy of Stone duality, and we also develop an effective definability technique which works up to homeomorphism. As an application, we show that there is a Polish space not homeomorphic to a computable one. We apply our techniques to build, for any computable ordinal, an effectively closed set not homeomorphic to any -computable Polish space; this answers a question of Nies. We also prove analogous results for compact Polish groups and locally path-connected spaces.