Re: [Info-gnuprologjava] FW: problem in creating complex prolog queries , queries created by conjugating more that 5 simple queries .

[Daniel Thomas]

On Thu, 2012-05-24 at 15:56 +0530, Suman Roy wrote:
> Hi,
> 
> We have tried using PrepareGoal, But gnu prolog is showing an error message, 
> “ Exception in thread "main" gnu.prolog.vm.PrologException: 
> error(system_error,'java.lang.StackOverflowError') ” . 
> 
> Unfortunately, the documentation does not have these details about using 
> PrepareGoal. It would be better if we know a little more about it. 
It is documented here: 
http://www.gnu.org/software/gnuprologjava/manual/Setup.html#Setup
and also (badly) here:
http://www.gnu.org/software/gnuprologjava/api/gnu/prolog/vm/Interpreter.html#prepareGoal(gnu.prolog.term.Term)

It might be cleaner to use CompoundTerm.getConjunction(Term head, Term
tail) to construct the goal. You might be nesting your conjunctions in
an odd way in that I think you are doing
','(','(','(p(x),q(y)),r(z)),s(l)) rather than
','(p(x),','(q(y),','(r(z),s(l))))

Maybe that is somehow causing the StackOverflowError. If you could get a
stacktrace of when this happens hten that would be great. Alternatively
if you attach a .java file I can just compile and run I could try and
get one.

Daniel

> Query intended to construct  :   :-  p(x) , q(y) , r(z),s(l). 
> 
> 
> 
> rules_01.pl file  :
> --------
> p (x).
> q(y).
> r(z).
> s(l ).
> 
> Code snippet : 
> -----------------
> 
> Term t1[]={AtomTerm.get("x")};
> Term t2[]={AtomTerm.get("y")};
>   Term t3[]={AtomTerm.get("z")};
>     Term t4[]={AtomTerm.get("l")};
> 
> 
> CompoundTerm ct1=new CompoundTerm("p",t1); 
>  CompoundTerm ct2=new CompoundTerm("q",t2);
> CompoundTerm ct3=new CompoundTerm("r",t3);
> CompoundTerm ct4=new CompoundTerm("s",t4);
> 
> String functor = ",";
> CompoundTerm mt1 = new CompoundTerm(functor, 2);
> mt1.args[0]=ct1;
> mt1.args[1]=ct2;
> CompoundTerm mt2 = new CompoundTerm(functor, 2);
> 
> mt2.args[0]=mt1;
> mt2.args[1]=ct3;
> 
> CompoundTerm mt3 = new CompoundTerm(functor, 2);
> mt3.args[0]=mt2;
> mt3.args[1]=ct4;
> 
> 
> Goal prepareGoal1 = in.prepareGoal(mt3);
> 
> 
>   int chk =in.execute(prepareGoal1);
> 
>            if (chk == PrologCode.SUCCESS || chk == PrologCode.SUCCESS_LAST) {
>                 System.out.println("Succesful execution ");
>             }
>            else {
>                 System.out.println("Failed execution ");
>            }
> 
> 
> Regards and thanks,
> --Suman
> 
> Suman Roy, Ph.D.
> Infosys LABS, 
> Infosys Technologies Ltd.,
> Bangalore, India.     
> Mob. +91 98860 23203 
> 
> 
> 
> -----Original Message-----
> From: Daniel Thomas [mailto:address@hidden 
> Sent: Wednesday, May 23, 2012 2:10 PM
> To: Suman Roy
> Cc: address@hidden; Jagadish Koneti
> Subject: Re: FW: problem in creating complex prolog queries , queries created 
> by conjugating more that 5 simple queries .
> 
> Sorry.
> 
> I think that the error message is misleading and due to a bug in the way I 
> used finally in my implementation of runOnce. Try using prepareGoal and then 
> execute (which is essentially what runOnce does) as then you should hopefully 
> get the correct error message when prepareGoal fails which should help with 
> working out what the actual problem is.
> 
> Daniel
> 
> On Thu, 2012-05-17 at 14:12 +0530, Suman Roy wrote:
> >  
> > 
> > Hello ,
> > 
> >  
> > 
> >    I want to construct a complex prolog query with the help of  “ gnu 
> > prolog “  jar file  , which will be conjugation of 5 simple prolog 
> > queries .
> > 
> >  
> > 
> > For instance :   :-   p (a) ,  q(b), r(c), s(d ), l(e )  .
> > 
> >  
> > 
> >   But gnu prolog is showing an error message , “ The goal is not 
> > currently active  ”. Can you please let me what can be done to create 
> > such queries?
> > 
> >  
> > 
> >  
> > 
> > rules_01.pl file  :
> > 
> > --------
> > 
> > p (a).
> > 
> > q(b).
> > 
> > r(c).
> > 
> > s(d ).
> > 
> > l(e )  .
> > 
> >  
> > 
> > Code snippet : 
> > 
> > -----------------
> > 
> >  
> > 
> > Term t1[] =  {AtomTerm.get("a")};
> > 
> > Term t2[] =  {AtomTerm.get("b")};
> > 
> >   Term t3[] =  {AtomTerm.get("c")};
> > 
> >   Term t4[] =  {AtomTerm.get("d")};
> > 
> >   Term t5[] = {AtomTerm.get("e”)};
> > 
> >  
> > 
> > CompoundTerm ct1=new CompoundTerm("p",t1);
> > 
> >  CompoundTerm ct2=new CompoundTerm("q",t2);
> > 
> > CompoundTerm ct3=new CompoundTerm("r",t3);
> > 
> > CompoundTerm ct4=new CompoundTerm("s",t4);
> > 
> > CompoundTerm ct5=new CompoundTerm("l",t5);
> > 
> >  
> > 
> > String functor = ",";
> > 
> > CompoundTerm mt1 = new CompoundTerm(functor, 2);
> > 
> > mt1.args[0]=ct1;
> > 
> > mt1.args[1]=ct2;
> > 
> > CompoundTerm mt2 = new CompoundTerm(functor, 2);
> > 
> >  
> > 
> > mt2.args[0]=mt1;
> > 
> > mt2.args[1]=ct3;
> > 
> >  
> > 
> > CompoundTerm mt3 = new CompoundTerm(functor, 2);
> > 
> > mt3.args[0]=mt2;
> > 
> > mt3.args[1]=ct4;
> > 
> >  
> > 
> > CompoundTerm mt4 = new CompoundTerm(functor, 2);
> > 
> > mt3.args[0]=mt3;
> > 
> > mt3.args[1]=ct5;
> > 
> >  
> > 
> >  
> > 
> >             int rc = in.runOnce(mt4);
> > 
> >  
> > 
> >  
> > 
> >  
> > 
> >  
> > 
> >  
> > 
> > =======================================
> > 
> >  
> > 
> > 
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