# Computer Science/Discrete Mathematics Seminar I

**Topic: **Choiceless Polynomial Time

**Speaker: **Ben Rossman

**Affiliation: **University of Toronto

**Date & Time: **Monday October 14th, 2019, 11:00am - 12:00pm

**Location: **Simonyi Hall 101

**Video:** https://video.ias.edu/csdm/2019/1017-BenRossman

The choiceless computation model of Blass, Gurevich and Shelah (1999, 2002) is an algorithmic framework for computing isomorphism-invariant properties of unordered structures. Machines in this model have the power of parallel execution, but lack the ability to make arbitrary choices. For example, a choiceless algorithm cannot freely select an arbitrary neighbor of a vertex in an unordered graph, but may execute a subroutine in parallel over all neighbors. In this talk, I will give an overview of results in the choiceless model and discuss the intriguing open question: Does every graph property that is decidable by a poly-time Turing machine admit a choiceless poly-time algorithm?