Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API

[Daniel Warzecha]

Hi,

yes, I found the manual, but it really didn't help me, I'm someone who learns best by example. The formatting on the manual is a bit off, also. 

So, by loading facts you mean load them from a prolog file? I wanted to use the library without resorting to loading prolog files at first, to see if I can programmatically build both knowledge base and rules. The second step will probably be building a prolog file to easily create the more complex rules.

ensureLoaded seems to load a prolog file and probably incorporate the facts etc. into the environment, am I right?

So if I have some Java strings which represent some atoms, e.g. "key1", is the following correct?

String keyAtom = "key1";

Environment prologEnv = new Environment();

AtomTerm.get(keyAtom); // creates the AtomTerm "key1" in the environment?

Or is there another way to put atoms in the environment?

Something like Environment.put(Term)? Environment.createFact(Term)?

Does stringToTerm(String,Environment) create a Term from the String and put it into the Environment?

And what about predicates (e.g. key/1) ? Is there a mechanism to let the environment know a predicate with an arity exists? Is the Predicate class used to do this?

Or rather, is the following correct?

String functor = "key";

int arity = 1;

Module mod = new Module();
Predicate keyPred = new Predicate(mod, CompoundTermTag.get(functor, arity));

And last but not least, to construct a CompoundTerm, e.g. key("key1"), what do I do?

Is the following correct?

String keyAtom = "key1";

String functor = "key";

CompoundTerm keyComp = new CompoundTerm(functor, keyAtom);

What do I have to do to incorporate the CompoundTerms and Predicates into the environment? Is this happening automatically?

Sorry for all the questions, I really don't understand the online manual yet.

Thanks for your help,

Daniel W. , Germany

2011/2/17 Daniel Thomas <address@hidden>

Hello,

Have you found the GNU Prolog for Java manual?
http://www.gnu.org/software/gnuprologjava/manual/

You can load prolog facts and rules using the ensureLoaded see
http://www.gnu.org/software/gnuprologjava/manual/Setup.html#Setup and
http://www.gnu.org/software/gnuprologjava/api/gnu/prolog/vm/Environment.html#ensureLoaded(gnu.prolog.term.Term)

If you are asserting facts at runtime then you do this as normal in
Prolog using assertz or asserta or similar (having previously declared
it to by dynamic as usual in a prolog file which you then ensureloaded)
- you can find instructions on creating terms here:
http://www.gnu.org/software/gnuprologjava/manual/Constructing-Terms.html#Constructing-Terms
or if you want to construct a term from a string (if you already have
the data you want as a string representation of a prolog term) then you
might want to use
http://www.gnu.org/software/gnuprologjava/api/gnu/prolog/io/TermReader.html#stringToTerm(java.lang.String, gnu.prolog.vm.Environment) though it doesn't look like that has been documented properly yet. Sorry.

Apologies that you found the API documentation irritating. I will try to
get it improved in the next release.

I hope this helps,

Daniel

On Thu, 2011-02-17 at 15:52 +0100, Daniel Warzecha wrote:
> Hello,
>
>
> I hope someone can help me. I'm trying to understand how to use the
> API in a correct way and am a bit overwhelmed.
>
>
> The background: I'm trying to parse messages in UML Sequence Diagrams
> and transform their facts, i.e. the message data to Prolog. Then I
> want to pose questions to the Prolog interpreter in regards to the
> knowledge base.
>
>
> Okay, sadly I don't understand how to do the following basic things
> with the API:
>
>
> 1. Tell the environment (if that's right) that some predicates exist:
> e.g. key/1 or knows/2 .
> 2. Tell Prolog that some facts exist: e.g. key("key1") or
> knows("attacker","key1")
> 3. Tell Prolog that certain rules exist: e.g.
> knows("attacker","message") :- encrypted("message","key1"),
> symmetricKey("key1").
>
>
> Can somebody please help me? The API docs only irritated me even more.
>
>
> Thanks in advance,
>
>
> Daniel W.