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∂AIL Miss Sylvia A Bressey, Assistant Registrar
↓Registrar's Office↓University of Essex↓Colchester CO4 3SQ∞

Dear Miss Bressey:

	I have had the following contacts with Pat Hayes.  He visited
the Stanford Artificial Intelligence Laboratory when he was a
graduate student, and we collaborated on a paper %2Some Philosophical
Problems from the Standpoint of Artificial Intelligence%1.  He
wrote the sections reviewing the relevant philosophical literature.
Since then I have followed his work through the computer science
literature.

	I know of two main areas in which he has contributed to
computer science - theorem proving in first order logic together
with using first order logic as a programming language and
epistemological problems of artificial intelligence.
In the first area, I would judge that his contributions have
been important, but I suppose not as influential as those of
Kowalski.

	In the very difficult field of the epistemological problems
of artificial intellgence, he is one of the very few people who
have stuck with the field other than myself.  Maybe he is the
only other person to make continued contributions.  I think the
field is very important, and when it opens out, as I expect it
will, I believe that Hayes's work will be found to be a source
of influential and important ideas.  By opening out, I mean that
a collection of technical problems will develop which can be
studied by people whose technical ability is less than their
ability to see a broad picture.

	Hayes is more important as an idea generator than as
a system builder.

	As to the day-to-day work of a university teacher, I have
no doubt that Hayes has and will continue to carry his share of
the load.  He has good sense, keeps his promises, co-operates
well with others, and shows leadership in practical matters as
well as in his specialty.

.sgn