[Axiom-developer] RE: What is SubDomain

[Bill Page]

Ralf,

I think perhaps we can view SubDomain as the first steps towards computing
with provisos (i.e. "provided that ...  clauses") and it is closely related
to the concept of "indefinite types" as explained by Tim Daly:

http://lists.gnu.org/archive/html/axiom-developer/2005-05/msg00205.html

http://wiki.axiom-developer.org/IndefiniteTypes

As Tim has pointed out, the Axiom algebra library does already contain a
domain called "SuchThat" that was among his first experiments in this
direction.

I think the the concept of NonNegativeInteger and PositiveInteger as
SubDomains of Integer are not so different from this. In a sense a
subdomain is just a domain with a proviso.

Regards,
Bill Page.