QUASAR weekly seminar talk.

• Date: Friday, October 3, 2025
• Time: 1:00 PM ET
• Location: STEM Complex
• Speaker: Connor Paddock
• Affiliation: University of Ottawa

Abstract

We show that it is undecidable to determine whether the commuting operator value of a nonlocal game is strictly greater than 1/2. As a corollary to our proof, there is a boolean constraint system (BCS) nonlocal game for which the value of the Navascues-Pironio-Acin (NPA) hierarchy does not attain the commuting operator value at any finite level. Our contributions involve establishing a computable mapping from Turing machines to BCS nonlocal games in which the halting property of the machine is encoded as a decision problem for the commuting operator value of the game. Our techniques are algebraic and distinct from those used to establish MIP*=RE. The talk will focus on decision problems for nonlocal game values and provide an overview of the topic and history of results.