Dr Peter Fletcher

My research interests are in artificial intelligence (especially connectionism and syntactic pattern recognition) and the philosophy of mathematics (especially intuitionism).

(Note: please e-mail me if you would like a copy of any of the papers listed below.)

Artificial Intelligence

1. Connectionist symbol processing.
I am working on self-configuring networks for unsupervised learning of recursive graph grammars. The 1991 and 1992 papers below describe a network that can learn simple (non-recursive) geometric structure from example patterns. The 2001 paper shows how the method can be extended to handle iterative structure. See the 1993 conference paper for a broader perspective on this project. Work in progress: robust symbol processing, recognition of noisy, vague, distorted, recursively structured patterns, in an inherently affine-invariant way. See EXAMPLES involving recognising several overlapping patterns. The following two papers refer to this work, and a full account will be published shortly.
2. Foundations of connectionist computation.
This is an investigation of the conceptual foundations of connectionism and its relation to other models of parallel processing. The result of this work is a general formal definition and semantics for connectionism, which is somewhat broader than the usual `weighted sum' models derived from McCulloch and Pitts.

Philosophy of Mathematics

I am an intuitionist. Fundamental to intuitionism are the notions of a mathematical construction and a constructive proof; I am working on clarifying these basic notions and the way they are used to provide an interpretation of predicate logic, number theory and analysis. I am also concerned to reconcile the intuitionistic view with important insights from Hilbert's formalism and logicism.

Full details are available in the following monograph:

For a broader perspective, including the implications for mathematical physics, see

I am also interested in nonstandard analysis; see

My current topics of interest are intuitionistic choice sequences and constructivist axiomatic geometry.

Last updated 17th February 2017.