Seminar series
Date
Thu, 05 Mar 2015
Time
11:00 -
12:30
Location
C5
Speaker
Ivan Tomasic
Organisation
QMUL
NOTE CHANGE OF TIME AND PLACE
It is known by results of Macintyre and Chatzidakis-Hrushovski that the theory ACFA of existentially closed difference fields is decidable. By developing techniques of difference algebraic geometry, we view quantifier elimination as an instance of a direct image theorem for Galois formulae on difference schemes. In a context where we restrict ourselves to directly presented difference schemes whose definition only involves algebraic correspondences, we develop a coarser yet effective procedure, resulting in a primitive recursive quantifier elimination. We shall discuss various algebraic applications of Galois stratification and connections to fields with Frobenius.