Re: [eclipse-clp-users] basic problem

From: Kish Shen <kisshen_at_...5...>
Date: Mon, 16 Feb 2009 17:54:25 +0000
Marcin Krol wrote:

> ..and I was under impression that I could use any predicate as bb_min's 
> Goal? How do I tell which predicate generates a search tree and which 
> does not?

What bb_min/3 actually requires is that you bind Cost within Goal, and 
the search returns the best (minimal) value of Cost.

sum(X,S) will only instantiate S (your cost variable) if X is a ground 
list of numbers, which it isn't in your program, as you don't have 
anything that will instantiate the variables in X. If you call bb_min 
with X as a ground list of numbers, then bb_min/3 will succeed, but it
is not very interesting, as there is no real search at all (sum/2 
returns only a single answer).

What you need for a real search are goals which will produce choices (if 
you are unfamiliar with this, you should probably read any Prolog 
textbook), like labeling/1 (there is (normally) more than one way to 
label your variables) and member/2 (if you have more than one element in 
your list, then there is more than one member).



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Received on Mon Feb 16 2009 - 17:54:51 CET

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