Re: [Yap-users] Forall/2 Problem

[Eyal D. <eya...@gm...>]

Clpfd is implemented using attributed variables, I think, so I think you'll have the same problem you did with diff/2.

Sent from my iPhone

> On Feb 23, 2016, at 9:26 AM, Edward Schwartz <esc...@ce...> wrote:
> 
> Hi Vitor and Eyal,
> 
> Thank you for responding.  We don't use any cuts in our own code.  We do
> use clpfd; I'm not sure how that is implemented internally, and whether
> it would cause problems with tabling.
> 
> When I use start_low_level_trace, some of the progress right before
> "why?" is printed is related to clpfd... which makes me think that might
> be responsible.
> 
> Does this seem like a possibility?
> 
> Many thanks,
> 
> Ed
> 
>> On 02/22/2016 05:45 PM, Vitor Santos Costa wrote:
>> hi Edward
>> 
>> If you compile YAP under debug mode, there are two predicates
>> 
>> :- start_low_level_trace.
>> 
>> :- stop_low_level_trace.
>> 
>> They will tell you all calls made. It is often a good idea to filter
>> them by using grep or by narrowing. 
>> 
>> The second point may be looking at the final tables, that may help too.
>> 
>> I'm forwarding this to Ricardo, he is the expert.
>> 
>> Best
>> 
>> Vitor
>> 
>> On Mon, Feb 22, 2016 at 9:56 PM, Eyal Dechter <eya...@gm...
>> <mailto:eya...@gm...>> wrote:
>> 
>>    HI Ed, there are all sorts of reasons this could print 'why?'. Its
>>    hard to say without knowing more about what your code does.  If the
>>    code is pure, I'm not sure why this would happen, but otherwise it's
>>    not hard to come up with examples. For example: 
>> 
>>     ?- [user].
>>     % consulting user_input...
>>    c(X) :- nonvar(X), !, fail. 
>>    |     c(1). 
>>    |     c(2).
>>    |      % consulted user_input in module user, 1 msec 0 bytes
>>    true.
>>     ?- forall(c(X), (c(X); writeln(why))).
>>    why
>>    why
>>    true.
>> 
>>    All any use of mutable variables, set_arg, asserta, or similar
>>    things can cause this. Not sure about tabling. 
>> 
>>    Eyal
>> 
>>    On Mon, Feb 22, 2016 at 3:28 PM, Edward Schwartz <esc...@ce...
>>    <mailto:esc...@ce...>> wrote:
>> 
>>        Hi all,
>> 
>>        I am encountering another strange problem.  It's difficult to
>>        reproduce
>>        in a small example, but should the following rule ever print "WHY?":
>> 
>>        testcase :-
>>            forall(foo(I, F, P, O, T, E, M),
>>                    (foo(I, F, P, O, T, E, M);
>>                    writeln('why?'))).
>> 
>>        Is it possible this is a bug relating to tabling (foo is
>>        tabled)?  How
>>        can I debug this?
>> 
>>        Thanks,
>> 
>>        Ed
>> 
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