Re: [eclipse-clp-users] How to expand domain of a variable

Yes, I know how to solve the problem procedurally (and I saw solutions
in different languages).
It's not the task I need to do for purpose, I'm just wondering if
implementing it in ECLiPSe can be easier than a in C++, for example.
For instance, I was thinking that built-in constraint reasoning can
help to merge overlapping intervals. But now I see that even
A::1..10 or A::1..20.
leaves several delayed goals and doesn't not just simplify to 1..20.

And after having domain I was thinking using simply ECLiPSe constraint
satisfaction

But now I see that probably all this wasn't a good idea.

Sergey.


On Sat, Nov 5, 2011 at 1:01 AM, Matthew Skala <mskala_at_cs.utoronto.ca> wrote:
> On Sat, 5 Nov 2011, Sergey Dymchenko wrote:
>> interval - the task is just to say Yes or No. An answer to a query
>> must be fast (definitely faster than just checking all intervals one
>> by one).
>>
>> Can this problem be solved effectively in ECLiPSe, or it doesn't look
>> as a good problem for CLP paradigm?
>
> If you're expanding the domains of variables other than by backtracking,
> then what you're doing isn't the CLP paradigm but something else.  I'm not
> even sure how expanding domains would be useful in solving this problem;
> what was the algorithm you were hoping to implement that made use of that
> operation?
>
> This problem could be solved by a standard interval-query data structure
> like the "interval tree."  Wikipedia has a rather confusing article by
> that name with references to standard textbooks; the texts would be a good
> place to start.  It amounts to building a binary tree on the intervals and
> then searching it - fairly standard intro data-structures stuff.  You
> could certainly implement the data structure in ECLiPSe, but I think you'd
> want to do that by basically procedural code written in ECLiPSe; I don't
> think trying to express it as a constraint satisfaction problem per se
> would be very convenient, though we can argue from theoretical principles
> that it necessarily must be *possible*.
> --
> Matthew Skala
> Postdoctoral Fellow, University of Manitoba
> mskala_at_cs.umanitoba.ca
>