Richard Heck rgheck at brown.edu
Wed Sep 19 19:52:13 EDT 2007

Bill Taylor wrote:
> Robinson's Q, does not prove commutativity.
> Therefore, it must presumably have models where one or both of
> additive or multiplicative commutativity fail.
> Are there any "easy" models of this type?
Yes. There are examples in Boolos[, Burgess, ] and Jeffrey. The point is 
that you can add non-standard elements quite freely, since there's not 
much to constrain their behavior.


Richard G Heck, Jr
Professor of Philosophy
Brown University
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