# Walter Dean

Research interests: Philosophy of mathematics, mathematical logic, history and philosophy of computation

Algorithmic and complexity theoretic barriers to mathematical understanding

The project bridges philosophy of mathematics and the study of algorithms and complexity in theoretical computer science. It concerns the significance of barriers -- i.e. mathematical results illustrating why certain problems currently believed to be "hard" cannot be resolved using existing proof techniques. Illustrative of such problems is the famous P vs NP question which asks whether the task of finding a solution to a certain kind of finite problem is intrinsically harder than that of verifying that a given solution is correct. A solution would have substantial ramifications -- e.g. for data security, quantum computation, and artificial intelligence. But after it was originally posed in 1971, P vs NP remains unsolved and is regarded as among the most difficult open problems in mathematics.

The discovery of barriers helps to explain this by illustrating how successive strategies for resolving P vs NP have failed. A central thesis of the project is that barriers illuminate not only technical impediments but also more general limitations of human knowledge both inside and outside mathematics. This theme will be explored in the context of sub-projects exploring the methodology of barriers as a case study in mathematical problem solving, the history of multiplication algorithms in the frame of the question "is it intrinsically more difficult to multiply than to add?" and complexity-theoretic limitations on the use of artificial intelligence for mathematical proof search.

Walter Dean is Associate Professor of Philosophy at the University of Warwick where he also convenes the joint degrees in Mathematics and Philosophy. His research focuses on philosophy of mathematics, mathematical logic, and the history and philosophy of computation. He has been particularly interested in interactions between computability and complexity theory and traditional questions about mathematical knowledge, proof, and justification.

His most recent projects have focused on applications of reverse mathematics to philosophical argumentation and the role of Gödel's completeness theorem in the latter stages of the Hilbert program. He has previously held fellowships from the Alexander von Humboldt Foundation, the *Agence Nationale de la Recherche*, and the Netherlands-America Foundation.