During February 22-23, 2013 I participated in the Sendai Logic School at Tohoku University in Sendai, Japan.
As part of the school, I gave an invited two-hour tutorial entitled Implicit definability in arithmetic.
My abstract is available in several formats: PDF, PS, DVI.
My slides are available in several formats: PDF, PS, DVI.
A list of my recent and upcoming talks is available.
My publication list is available.
simpson@math.psu.edu / 25 February 2013