Re: ...Contemplating unspecified constraint SOLVERS.
- From: "Dirk Mittler" <mdirk@xxxxxxxxxxxx>
- Date: Fri, 26 Aug 2005 22:29:40 -0400
"A.L." <alewando_won_@xxxxxxxxxxxxxxx> wrote in message
news:9v7pg1pr95s0q0dh6nl95fpqm70ra2fkpb@xxxxxxxxxx
> On Mon, 22 Aug 2005 09:13:44 -0400, "Dirk Mittler"
> <mdirk@xxxxxxxxxxxx> wrote:
>
>>I'm still very much a newbie at Prolog, but one of my first experiments
>>was
>>to write some code which attempted to find contradictions in the
>>constraints
>>or attributes of unbound variables, at a point in time before they could
>>be
>>instantiated.
> [...]
>>
>>And to me this generalized test is probably not worth the effort for most
>>kinds of programming any more. On the other hand, I also did not put much
>>effort into writing it either.
>>
>
> Could you please summarize in one SHORT paragraph what is your
> point?...
>
> A.L.
You are focussing on the fact that an earlier exercise of mine, which people
would have a hard time even to find on the bulletin board by now, was in
fact not functional, and that yet I spent time on it. But I believe that one
would need to understand precisely the text which you have omitted here, in
order to begin to write one's own constraint *solvers* . As opposed to just
using a CLP(R) solving system that came with the Prolog compiler.
And Ivan Bratko's book nowhere explains how to write your own constraint
solver. Instead, it assumes that people can simply set up their constraint
systems, where even with CLP(R) , only a limited set of operators is
allowed between the " {} " braces. Of course, one can define one's own
constraint entirely in terms of an existing constraint library, including
some derivatives if those functions are not provided... But otherwise to
write a constraint solver requires that one understands the CHR, how that
relates to attributed variables, and so on. It actually requires much more.
But since it was probably not your intention to omit this information, I
will assume for the moment that my posting had no point, and that your use
of CLP is to apply constraints which have been defined for you.
In that case, I can imagine that more linguistic confusion is possible, even
though you did not take part in the debate yourself of what 'my' book means.
For example, to apply CLP(R) operators many times could be stated as
defining a constraint *system* , for example to declare a Physics problem.
But to define these operators is actually the core of defining the actual
*constraints* . Which are therefore no longer really operators... And my
exercise had as importance to me, to bring me to the point of realizing all
of this. Even though I'm just a novice at Prolog.
I've actually been programming for 30 years or so, and for this reason
expect myself to have a more ambitious comprehension of any new language,
even if this language, new to me, brings entirely new programming logic. And
I do not feel that *my own* past experiences in BASIC and then C++ will be
that much of a handicap for learning Prolog, because I readily take to
abstract logic. In spite of still only having glanced at Prolog a few times
so far. I have so many activities to spend time on instead, that my Prolog
compiler really gathers dust.
Dirk
.
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