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Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Pro
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From: |
Daniel Thomas |
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Subject: |
Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API |
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Date: |
Tue, 22 Feb 2011 17:14:31 +0000 |
Hello,
> But if I use runOnce with the goal, it always produces the first
> result as VariableTerm.value. I couldn't find a continue or
> getAllResults or something like that so far. Maybe you could help?
If you want to run it more than once you should not be using runOnce
(hence the Once in runOnce) you should instead be using execute(Goal)
after using prepareGoal(Term) as per the documentation in
http://www.gnu.org/software/gnuprologjava/manual/Setup.html#Setup
> Additionally, my knowledge base has atoms with an underscore "_" in
> their name. I know that you have to use quotation marks (") to mask
> those names. I hope I'm already doing it the right way, but could you
> double-check?
> String key = "k_c";
> Term [] invkeyArg = {AtomTerm.get("\"" + key + "\"")};
> CompoundTerm [] invkeyComp =
> {new CompoundTerm(AtomTerm.get("inverseOf"), invkeyArg)};
> CompoundTerm assertCT = new CompoundTerm("asserta",invkeyComp);
You really don't want to be using double quotes to construct atom terms.
It won't do what you first think of in prolog. Unless you have changed
the default value of the double_quotes flag from codes to atom then you
will get a list of the ascii character codes of the contents of the
double quotes which is most likely not what you are after.
Underscores in atom terms are fine as long as they don't occur as the
first character. If they do then you want to be using single rather than
double quotes.
We might want to switch to using the savannah support tracker for
tracking this rather than the mailing list.
https://savannah.gnu.org/support/?group=gnuprologjava
Sorry for the slow reply I have a lot of deadlines at the moment.
Daniel
On Sun, 2011-02-20 at 20:34 +0100, Daniel Warzecha wrote:
> Hello,
>
>
>
> thank you for helping so far, it seems I can finally run goals.
>
>
> At the moment I'm having the problem that I want to see all variable
> values that a certain goal could "create". To test my knowledge base I
> want to output all keys in my KB.
>
>
> But if I use runOnce with the goal, it always produces the first
> result as VariableTerm.value. I couldn't find a continue or
> getAllResults or something like that so far. Maybe you could help?
>
>
> Additionally, my knowledge base has atoms with an underscore "_" in
> their name. I know that you have to use quotation marks (") to mask
> those names. I hope I'm already doing it the right way, but could you
> double-check?
> String key = "k_c";
> Term [] invkeyArg = {AtomTerm.get("\"" + key + "\"")};
> CompoundTerm [] invkeyComp =
> {new CompoundTerm(AtomTerm.get("inverseOf"), invkeyArg)};
> CompoundTerm assertCT = new CompoundTerm("asserta",invkeyComp);
>
>
> Am I doing it right? Or does the API automatically mask Strings with
> underscores?
>
>
>
> Greetings and many thanks so far,
> Daniel W.
>
>
> 2011/2/18 Daniel Thomas <address@hidden>
> Hello,
>
> > Term [] isKeyArgs = {AtomTerm.get("aKey")};
> > String functor = "isKey";
> > CompoundTerm isKeyCompTerm = new CompoundTerm(functor,
> isKeyArgs);
> > theInterpreter.runOnce("asserta(""isKeyCompTerm"")");
>
> That won't work as there is no method in Interpreter called
> runOnce
> which takes a String as an argument. See:
>
> http://www.gnu.org/software/gnuprologjava/api/gnu/prolog/vm/Interpreter.html#runOnce(gnu.prolog.term.Term)
>
>
> > String assertFunctor = "asserta";
> > CompoundTerm assertCT = new CompoundTerm(assertFunctor,
> > isKeyCompTerm);
> > theInterpreter.runOnce(assertCT);
>
> Almost. If you look in
>
> http://www.gnu.org/software/gnuprologjava/api/gnu/prolog/term/CompoundTerm.html
> you will see that there is no constructor which takes a String and a Term.
> However there is one which takes a String and a Term[] which is what you used
> for isKeyCompTerm and is what you want.
>
> So what you want is something akin to:
>
> Term [] isKeyArgs = {AtomTerm.get("aKey")};
>
> CompoundTerm[] isKeyCompTerm = {new CompoundTerm("isKey",
> isKeyArgs)};
> CompoundTerm assertCT = new CompoundTerm("asserta",
> isKeyCompTerm);
> theInterpreter.runOnce(assertCT);
>
> Or alternatively:
>
> Term assertIsKeyAKey =
> TermReader.stringToTerm("asserta(isKey(aKey))",environment);
> interpreter.runOnce(assertCT);
>
> The former is better though and should run faster.
>
>
> I hope this helps,
>
> Daniel
>
>
> On Fri, 2011-02-18 at 17:58 +0100, Daniel Warzecha wrote:
> > Hello,
> >
> >
> > thank you for your help, and I am very sorry that I am
> obviously so
> > thick in the head, but I have some more questions:
> >
> >
> > Let's assume I have built the prolog file to load into the
> environment
> > with ensureLoaded...
> > If I load it, the facts in the file are present in the
> environment.
> >
> >
> > Okay, you're telling me to use asserta or assertz to make my
> compound
> > terms.
> >
> > So what would be the code to create the term isKey("aKey")
> from start
> > to finish?
> >
> > I'm trying again first:
> > Term [] isKeyArgs = {AtomTerm.get("aKey")};
> > String functor = "isKey";
> > CompoundTerm isKeyCompTerm = new CompoundTerm(functor,
> isKeyArgs);
> > theInterpreter.runOnce("asserta(""isKeyCompTerm"")");
> >
> >
> > Or maybe more:
> > String assertFunctor = "asserta";
> > CompoundTerm assertCT = new CompoundTerm(assertFunctor,
> > isKeyCompTerm);
> > theInterpreter.runOnce(assertCT);
> >
> >
> > Thanks in advance,
> > Daniel Warzecha
> >
> > 2011/2/17 Daniel Thomas <address@hidden>
> > Hello,
> >
> > The html version of the manual does appear to be a
> bit broken.
> > The info
> > version should work better
> >
> http://www.gnu.org/software/gnuprologjava/manual.info
> >
> > You can load facts programatically if you define the
> predicate
> > to be
> > dynamic beforehand in the standard manner for
> prolog.
> > :-dynamic(predicate/n).
> > However that declaration needs to be in a file which
> you load
> > using
> > ensureLoaded and after which you then have called
> > runInitialisation
> >
> > You should be able to define both rules and facts
> > programatically at
> > runtime if you have previously declared the relevant
> > predicates to be
> > dynamic in a file. (In a future version we will
> support
> > loading text
> > straight from a reader or similar without having to
> use a file
> > at all
> > but at the moment at least one file is necessary to
> define the
> > existence
> > of the predicates).
> >
> > I will continue answering inline.
> >
> > On Thu, 2011-02-17 at 17:36 +0100, Daniel Warzecha
> wrote:
> > > 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?
> >
> >
> > Yep.
> >
> > > 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?
> >
> > Nope. AtomTerm.get(keyAtom) returns an AtomTerm (see
> the
> > return type).
> > If by in the environment you mean such that
> > :- key1.
> > would succeed then that won't work. There isn't a
> neat way of
> > making
> > that work at present (ensureLoading from a string or
> a term
> > would be
> > neater) the difficulty being in managing a new kind
> of unique
> > identifier
> > as we wouldn't be able to use filenames any more and
> Prolog
> > cares about
> > where things came from.
> > Since you probably can't predefine key1 etc. to be
> dynamic
> > that might
> > cause problems but you can easily define key/1 to be
> dynamic
> > and then
> > declare at runtime key(key1) etc. using assert[az].
> >
> > > Or is there another way to put atoms in the
> environment?
> > > Something like Environment.put(Term)?
> > Environment.createFact(Term)?
> >
> >
> > No. The problem is that a declared term to exist in
> the
> > Environment
> > needs to have a declaring file (or something
> similar) and we
> > don't have
> > the something similar working yet (I haven't given
> much
> > thought as to
> > how to go about doing that yet).
> >
> > > Does stringToTerm(String,Environment) create a
> Term from the
> > String
> > > and put it into the Environment?
> >
> >
> > Nope stringToTerm creates the Term object from the
> string -
> > essentially
> > it simply causes it to be parsed into a Term object
> - which
> > you could
> > then execute. It doesn't cause it to go through the
> guts of
> > PrologTextLoader as that needs a file in order to
> know where
> > things came
> > from.
> >
> > > And what about predicates (e.g. key/1) ? Is there
> a
> > mechanism to let
> > > the environment know a predicate with an arity
> exists?
> >
> >
> > Yes :- dynamic(key/1) as in the prolog standard.
> >
> > > Is the Predicate class used to do this?
> >
> > Nope. You shouldn't be using the Predicate class for
> anything
> > except
> > perhaps if you were extending GNU Prolog for Java by
> defining
> > new built
> > in predicates (and then only if they were doing odd
> things
> > with the
> > internal representation of Prolog terms).
> >
> > > 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));
> >
> >
> > No that is very wrong. Don't do that.
> > I should probably create and change the permissions
> on the
> > constructor
> > for Module so that that isn't even possible.
> >
> > As a user of the library you want to be using
> Environment and
> > Interpreter along with some of the classes in
> gnu.prolog.term
> > These
> > classes have better documentation than the rest
> (though that
> > is still
> > not saying as much as I would like - I haven't yet
> got around
> > to going
> > through the whole library and adding documentation
> everywhere
> > as when I
> > took over maintenance there was essentially none.)
> >
> > > 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);
> >
> > No. There is no constructor which takes those
> arguments. All
> > the
> > constructors are documented
> >
>
> http://www.gnu.org/software/gnuprologjava/api/gnu/prolog/term/CompoundTerm.html
> > You probably want something along the lines of
> > Term[] keyAtom = {AtomTerm.get("keyAtom")};
> > String functor = "key";
> > CompoundTerm keyComp = new
> CompoundTerm(functor,keyAtom);
> >
> > As that should create a compound term of with the
> correct
> > functor and
> > use the arity from keyAtom to determine the arity
> and fill its
> > arguments
> > with an atom keyAtom.
> >
> > > What do I have to do to incorporate the
> CompoundTerms and
> > Predicates
> > > into the environment? Is this happening
> automatically?
> >
> >
> > As above don't use Predicate. To incorporate a
> CompoundTerm
> > into the
> > environment dynamically you will want to use
> > Interpreter.runOnce
> >
>
> http://www.gnu.org/software/gnuprologjava/api/gnu/prolog/vm/Interpreter.html#runOnce(gnu.prolog.term.Term)
> > as per
> >
> http://www.gnu.org/software/gnuprologjava/manual/Setup.html#Setup
> > with an argument containing an assert[az]/1 term
> with the
> > CompoundTerm
> > as the argument.
> > you want assertz(key(keyAtom)) or something similar.
> >
> > > Sorry for all the questions, I really don't
> understand the
> > online
> > > manual yet.
> >
> >
> > I will try and get the manual improved in the next
> release.
> >
> > > Thanks for your help,
> > > Daniel W. , Germany
> >
> >
> > I hope this helps,
> >
> > Daniel
> >
> > > 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.
> > >
> > >
> > >
> >
> >
> >
>
>
>
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- [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Warzecha, 2011/02/17
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Thomas, 2011/02/17
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Warzecha, 2011/02/17
- Message not available
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Thomas, 2011/02/18
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Warzecha, 2011/02/20
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API,
Daniel Thomas <=
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Warzecha, 2011/02/22
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Thomas, 2011/02/22
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Warzecha, 2011/02/22
- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Thomas, 2011/02/25
- Message not available
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- Re: [Info-gnuprologjava] Problems understanding the usage of the GNU Prolog API, Daniel Warzecha, 2011/02/28