An Interview with
University of Chicago’s Robert Soare, the Paul Snowden Russell Distinguished Service
Professor of Mathematics and Computer Science, offers his reflections on Alan Turing.
Interviewed by Arefin Huq
AREFIN HUQ: Your upcoming book is
entitled, Computability Theory and
Applications, and it’s subtitled, “The art
of classical computability.” Why did you
choose that title?
ROBER T SOARE: Mathematicians value
work on the basis of beauty. It has to be
correct, but the question is: Is it beautiful?
Is it a beautiful theorem, a beautiful proof?
At the University of Chicago no one asks me
to do the mathematics of building bridges
on a deadline. I choose the problems that
I work on, and I choose problems for my
students, and they work on the things they
enjoy doing. We do it because we hope to
solve important problems but we do it also
because it’s beautiful. So the subtitle, “The
art of classical computability,” is supposed
to represent this thought.
Photograph by Olin Mills
AH: What makes Turing’s model of
computation so compelling?
RS: Why do we give so much credit to
Turing? His advisor, Alonzo Church, was
already a professor before Turing even
started out, and Church proposed one
definition of computable function in 1934,
the lambda-definable functions, and
another one in 1935. Church got it right,
twice, and he got it first. He got it right in
the sense that he proposed a model which
later proved to be correct. Turing came on
the scene only in 1936, when he published
his paper after Church’s paper was already
announced and published. And yet if you
pick up any book on computability now
you’ll see a description of a Turing machine.
You won’t see the lambda-definable
functions of Church and you won’t see the
recursive functions of Herbrand-Gödel, but
you will see Turing’s model because it is
easy to understand. That’s the first part.