CLP(FD): what is necessary?

Dnia Fri, 14 Mar 2008 13:56:56 +0000
Kish Shen <kishshen@yahoo.com> napisa=C5=82(a):

> Joachim Schimpf wrote: 
=20 
>=20
> The other main reason is for debugging, especially if your debugging=20
> code (e.g. the debugger itself) is written in the source language, like=20
> ECLiPSe. You want this code to run at a very high priority, so that the=20
> state of the code you are debugging does not change as you are running=20
> the debugger code.
>=20
I do understand a need for debugging. But it would be MUCH
simpler and cleaner if debugging goals were not mixed with constraints.
User should declare that this goal is for debugging. System should
first evaluate debugging goals before evaluating other goals.
It is not good to use the same priority system for debugging and
constraints.

Best regards
--=20
[ Wit Jakuczun    <W.Jakuczun [at] wlogsolutions.com> ]
[ WLOG Solutions  http://www.wlogsolutions.com ]

Dnia Fri, 14 Mar 2008 10:06:28 -0500
"Neng-Fa Zhou" <nzhou@acm.org> napisa=C5=82(a):

> "Wit Jakuczun" <wit@mefisto.hades> wrote in message=20
> news:20080313124649.580be484@mefisto.hades... 
>=20
> A successor of Delay Clauses, called Action Rules, have been developed fo=
r=20
I have noticed Action Rules but I have not tried them.
What is the main difference between Action Rules and Delay Clauses?
Action Rules looks similar to CHR. What are the main
differences?

Best regards
--=20
[ Wit Jakuczun    <W.Jakuczun [at] wlogsolutions.com> ]
[ WLOG Solutions  http://www.wlogsolutions.com ]

On 2008-03-14, A.L <alewando@zanoza.com> wrote:
> On 14 Mar 2008 13:31:56 GMT, Jan Wielemaker <jan@nospam.ct.xs4all.nl>
> wrote:
> 
>
> OK, but what standard says about this? Does it say at all?...

Nothing.  Many Prolog systems take the freedom to add more evaluable
functions.  This is just one example.  If you use it, it will work on
ECLiPSe, SWI-Prolog >= 5.6.53 and if I understand Vitor on the next
YAP release.  On most other systems you get an exception.  If there is
a good and portable type system for which having eval(_) is useful, it
will eventually get more popular and ISO standard.  Dream dream ...

Cheers --- Jan

On Fri, 14 Mar 2008 10:06:28 -0500, "Neng-Fa Zhou" <nzhou@acm.org>
wrote:

>"Wit Jakuczun" <wit@mefisto.hades> wrote in message
>news:20080313124649.580be484@mefisto.hades... 
>
>A successor of Delay Clauses, called Action Rules, have been developed for
>implementing constraint propagators. Take a look at my TPLP paper

Cannot find this paper.... Could you provide a link?...

A.L.

"Joachim Schimpf" <jschimpf@cisco.com> wrote in message
news:1205504359.212176@sj-nntpcache-3.cisco.com...
> Neng-Fa Zhou wrote:
> ... 
>
> I don't think you should say that, because they are conceptually
> very different.  Delay clauses are meta level annotations that
> don't affect the declarative meaning of the program (you can remove
> them without changing the meaning of your prgram).  If I am not mistaken,
> Action rules do affect the meaning (because they contain "actions"),
> right?

I call (AR) Action Rules a successor of (DC) Delay Clauses because  AR is
inspired by DC and AR subsumes DC (A delay clause is a special action rule
where the events watched are only ins events and the action is just true).

Cheers,
Neng-Fa

"A.L." <alewando@zanoza.com> wrote in message
 news:vu9lt3haj2e3monvomvksptsm9j1qomkot@
4ax.com...
> On Fri, 14 Mar 2008 10:06:28 -0500, "Neng-Fa Zhou" <nzhou@acm.org>

> Cannot find this paper.... Could you provide a link?...

"Programming Constraint Propagation in Action Rules"
http://www.sci.brooklyn.cuny.edu/~zhou/papers/arule.pdf
arxiv.org/pdf/cs.PL/0506005

Here is another paper you might be interested in, which has been rejected
four times and yet to find a place to get published.

"The dom event and its use in implementing constraint propagators",
http://www.cs.gc.cuny.edu/tr/techreport.php?id=208

I have a plan to write a tutorial on the use of Action Rules to implement
constraint propagators for a wide range of constraints including linear,
non-linear, extensional, and global constraints. I'll keep you posted.

Cheers,
Neng-Fa

> I have noticed Action Rules but I have not tried them.
> What is the main difference between Action Rules and Delay Clauses?
> Action Rules looks similar to CHR. What are the main
> differences?

CHR tends to be higher-level than either Action Rules or Delay
Clauses.
While the other features are only available in one (or two?) system,
CHR is be availabe in Eclipse, SWI-Prolog, Yap, Ciao, SICStus, XSB
and hProlog.

You can find lots of material on the CHR website:
http://www.cs.kuleuven.be/~dtai/projects/CHR/

There is also a paper by the Action Rules and CHR implementors on
implementing CHR with Action Rules, which may be useful to see some
of the differences:
* CHR workshop version:
http://www.cs.kuleuven.ac.be/cgi-bi...nfo.pl?id=42254
* technical report:
http://www.cs.kuleuven.be/publicati.../CW449.abs.html

Cheers,

Tom

On Fri, 14 Mar 2008 13:15:12 -0500, "Neng-Fa Zhou" <nzhou@acm.org>
wrote:

>
>"A.L." <alewando@zanoza.com> wrote in message
> news:vu9lt3haj2e3monvomvksptsm9j1qomkot@
4ax.com... 
> 
>
>"Programming Constraint Propagation in Action Rules"
>http://www.sci.brooklyn.cuny.edu/~zhou/papers/arule.pdf
>arxiv.org/pdf/cs.PL/0506005
>
>Here is another paper you might be interested in, which has been rejected
>four times and yet to find a place to get published.
>
>"The dom event and its use in implementing constraint propagators",
>http://www.cs.gc.cuny.edu/tr/techreport.php?id=208
>
>I have a plan to write a tutorial on the use of Action Rules to implement
>constraint propagators for a wide range of constraints including linear,
>non-linear, extensional, and global constraints. I'll keep you posted.
>

Thanks!

A.L.

On Fri, 14 Mar 2008 11:33:34 -0700 (PDT), Annemie Janssens
<janssens.annemie@gmail.com> wrote:
 
>
>CHR tends to be higher-level than either Action Rules or Delay
>Clauses.
>While the other features are only available in one (or two?) system,
>CHR is be availabe in Eclipse, SWI-Prolog, Yap, Ciao, SICStus, XSB
>and hProlog.
>
>You can find lots of material on the CHR website:
>http://www.cs.kuleuven.be/~dtai/projects/CHR/
>
>There is also a paper by the Action Rules and CHR implementors on
>implementing CHR with Action Rules, which may be useful to see some
>of the differences:
>* CHR workshop version:
>http://www.cs.kuleuven.ac.be/cgi-bi...nfo.pl?id=42254
>* technical report:
>http://www.cs.kuleuven.be/publicati.../CW449.abs.html
>

Thanks for pointers; finally I know how CHR works :)

A.L.

On Fri, 14 Mar 2008 11:33:34 -0700, Annemie Janssens wrote:

> CHR tends to be higher-level than either Action Rules or Delay
> Clauses.
> While the other features are only available in one (or two?) system,
> CHR is be availabe in Eclipse, SWI-Prolog, Yap, Ciao, SICStus, XSB
> and hProlog.

Note that these two statements are about orthogonal issues: availability
and level.

But both seem to be true - for the second statement, just look at the
manuals and count.

For the first statement: the CHR language proper does never refer to the
degree of instantiation of a source level variable, and it has no explicit
language construct to postpone something. All this is implicit in the
semantics of the guards, and the matching in the heads (something
partially true in action rules). The other big difference is that in CHR,
one can express in the head a conjunction of truths, while action rules
(and delay clauses) only allow for inference based on (search for) single
truths.


Cheers

Bart Demoen