[FOM] Primitive recursive reals
Timothy Y. Chow
tchow at alum.mit.edu
Fri Apr 21 13:20:05 EDT 2006
Joe Shipman wrote:
> The whole discussion seems to suggest that maybe we should seek to
> reformulate constructive analysis in terms of a representation of real
> numbers that has nicer properties than "base b" notation; a
> representation in which the standard arithmetic operations preserve
> primitive recursivity (and, it is to be hoped, preserve much sharper
> computational properties such as polynomial-time computability).
I mentioned this to Joe Shipman directly, but then figured maybe it's
worth posting to FOM.
It's long been appreciated that base-b representations are the wrong
representation for computational questions. There is a fairly good
understanding now of how to represent real numbers in a robust manner that
allows issues of, say, computational complexity to be addressed (although
the subject is still immature compared to classical recursion theory, and
many important foundational questions remain unanswered). A good
introduction to the subject is an article that I think has already been
mentioned on FOM, namely Braverman and Cook's article in the March 2006
Notices of the AMS: "Computing over the Reals: Foundations of Scientific
Computing."
This does not address Joe Shipman's specific question about *canonical*
representations, though.
Tim
More information about the FOM
mailing list