Re: [boost] Formal Review for Interval Library beginning

From: Guillaume Melquiond (gmelquio_at_[hidden])
Date: 2002-09-06 11:43:37

On Fri, 6 Sep 2002, Fernando Cacciola wrote:

> > The problem is not in the user supplying such a mapping. But the user may
> > want raw results rather than mapped results.
> I don't understand what you mean with raw/mapped results.
> Isn't interval-interval comparisons *always* mapped?

Let's put it simply: the result of a comparison (in the forall/exists
context used in static analysis and inequations systems solving) is an
element of {false, maybe, true}. You need three different values; and if
you map it to {false, true} before returning it to the user, he/she will
lose a part of the information.

By using a more complex type than bool, you can store this three-states
information. And the problem of this type being convertible or not to bool
afterwards is not really relevant here. What is interesting with tribool
is that it holds a three-states value, not that it is convertible to bool.

Regards,

Guillaume