During October 18-21, 2007 I participated in a Dynamical Systems Workshop here at the
Pennsylvania State University. I gave a one-hour talk on
** Degrees of unsolvability of 2-dimensional subshifts of finite
type**. My abstract is available in several formats: PDF, PS, DVI, HTML, plain text. My slides are available in
several formats: PDF, PS.

A list of my recent and upcoming talks is available.

My publication list is available.

t20@psu.edu / 18 October 2007