Seminar series
Date
Thu, 17 Oct 2013
Time
17:15 -
18:15
Location
L6
Speaker
Jochen Koenigsmann
Organisation
Oxford
We give a negative answer to Abraham Robinson's question whether a finitely generated extension of an undecidable field is always undecidable by constructing undecidable fields of transcendence degree 1 over the rationals all of whose proper finite extensions are decidable. We also construct undecidable algebraic extensions of the rationals which allow decidable finite extensions.