The Borel complexity of the class of models of first-order theories
- 17 July 2025
- journal article
- Published by American Mathematical Society (AMS) in Proceedings of the American Mathematical Society
- Vol. 153 (09) , 4013-4024
Abstract
We investigate the descriptive complexity of the set of models of first-order theories. Using classical results of Knight and Solovay, we give a sharp condition for complete theories to have a Π ω 0 \boldsymbol \Pi _\omega ^0 -complete set of models. In particular, any sequential theory (a class of foundational theories isolated by Pudlák) has a Π ω 0 \boldsymbol \Pi _\omega ^0 -complete set of models. We also give sharp conditions for theories to have a Π n 0 \boldsymbol \Pi ^0_n -complete set of models.Keywords
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Funding Information
- National Science Foundation (2348792)
- National Science Foundation (626304)
- National Science Foundation (10.55776/P36781.)
- National Science Foundation (101026834 - ACOSE)
- Simons Foundation (2348792)
- Simons Foundation (626304)
- Simons Foundation (10.55776/P36781.)
- Simons Foundation (101026834 - ACOSE)
- Austrian Science Fund (2348792)
- Austrian Science Fund (626304)
- Austrian Science Fund (10.55776/P36781.)
- Austrian Science Fund (101026834 - ACOSE)
- H2020 Marie Skłodowska-Curie Actions (2348792)
- H2020 Marie Skłodowska-Curie Actions (626304)
- H2020 Marie Skłodowska-Curie Actions (10.55776/P36781.)
- H2020 Marie Skłodowska-Curie Actions (101026834 - ACOSE)
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