The field-type conjecture for NIP expansions by closed sets

About 7 years old · traced to

Let R{\mathscr{R}} be an NIP expansion of (R,<,+)(\mathbb{R},<,+) by closed subsets of Euclidean space. Call R{\mathscr{R}} field-type when it satisfies condition (1): there is a nonempty open interval II and continuous definable operations ⊕,⊗:I2→I\oplus,\otimes:I^2\to I such that (I,<,⊕,⊗)(I,<,\oplus,\otimes) is an ordered field isomorphic to (R,<,+,×)(\mathbb{R},<,+,\times). Field-type conjecture. If R{\mathscr{R}} interprets an infinite field, then R{\mathscr{R}} is field-type. The conjecture concerns whether interpreting an infinite field in this tame setting necessarily yields a definable real field on an interval; the paper proves several special cases and notes that the formulation can be changed from interprets to defines under definable selection.

References

Primary source

Erik Walsberg, “Externally definable quotients and NIP expansions of the real ordered additive group”, arXiv:1910.10572 (2020).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.