Problem with a crosswords generator

Hi everybody,

I have a problem with my prolog program, which is a crosswords generator :
When I call :
?- consult('code.txt').
?- genereMC(L).

It finds : L = [0, 0, 0, 97, 98, 99, 0, 0, 0]

which corresponds to
???
abc
???
(0 are "black cases")
whereas this solution is false because I only want to have isolated black
cases.

The most surprising is that
?- genereMC([0, 0, 0, 97, 98, 99, 0, 0, 0]).
answers NO !!!

Where is my mistake ? (I use SWI-Prolog)

I give you my code (NB : I'm french) :
'liste_francais_3.txt' contains a list of words like that :
mot("abc").
mot("adn").
mot("afp").
mot("age").
mot("age").
mot("agi").
mot("ah").
etc....

----------------------------------------------------------------------------
------------------

/* Charge la liste de mots */

?-consult('liste_francais_3.txt').


/*--------------------------------------------------------------------------
----*/
/*---------------------------
verifLigne ---------------------------------------*/
/*--------------------------------------------------------------------------
----*/

/* Cas de l'appel de la fonction (2e parametre par défaut = [])  */
verifLigne(L) :- verifLigne(L, []).

/* Quand on arrive au bout de la ligne */
verifLigne([], []).
verifLigne([], MotCourant) :- mot(MotCourant).

/* Quand on rencontre "un carré noir" */
verifLigne([0], []).
verifLigne([0], MotCourant) :- mot(MotCourant).
verifLigne([0|[X|R]], []) :- X\==0, verifLigne([X|R], []).
verifLigne([0|[X|R]], MotCourant) :- X\==0, mot(MotCourant),
verifLigne([X|R], []).

/* Cas général */
verifLigne([X|R], MotCourant) :- X\==0, append(MotCourant, [X],
NewMotCourant), verifLigne(R, NewMotCourant).


/*pasDeLettresIsolees(MC).*/


verifMotCroise([A,B,C,D,E,F,G,H,I]) :- verifLigne([A,B,C]),
verifLigne([D,E,F]), verifLigne([G,H,I]),

verifLigne([A,D,G]), verifLigne([B,E,H]), verifLigne([C,F,I]).

affich([A,B,C,D,E,F,G,H,I]) :- name(L1, [A,B,C]), name(L2, [D,E,F]),
name(L3, [G,H,I]), write(L1), nl, write(L2),

nl, write(L3), nl.

genereMC(L) :- verifMotCroise(L), affich(L).

Hi!

The reason you get multiple black squares is that when the
variable X is not instantiated, the X \== 0 expression will be
true, but that does not mean, that when X becomes instantiated,
it cannot take the value 0.
That is why genereMC/1 generates invalid crossword puzzles, however
when all variables are instantiated at the beginning (calling the predicate
with the [0,0,0,97,98,99,0,0,0] argument), it will correctly recognize
that is is an invalid puzzle.

Here is how I would generate (and test) the validity of lines of puzzle

% La ligne commence avec un carre noir
verifLigne([0|L]) :- verifLigne2(L).

% La ligne ne commence pas avec un carre noir
verifLigne(L) :- verifLigne2(L).

% Cas #1) Fin de la ligne.
verifLigne2([]) :- !.

% Cas #2) Tout le reste est un mot.
verifLigne2(L) :- mot(L).

% Cas #3) Il y a un mot, suivant par un carre noir, est des autres mots.
verifLigne2(L) :- append(M, [0|L2], L), mot(M), verifLigne2(L2).

Sorry for my French, I haven't used it for a long time.

Dave


The
"Spoofix" <xxx@xxx.xxx.invalid> wrote in message
news:416ebd92$0$27928$626a14ce@news.free.fr...
> Hi everybody,
>
> I have a problem with my prolog program, which is a crosswords generator :
> When I call :
> ?- consult('code.txt').
> ?- genereMC(L).
>
> It finds : L = [0, 0, 0, 97, 98, 99, 0, 0, 0]
>
> which corresponds to
> ???
> abc
> ???
> (0 are "black cases")
> whereas this solution is false because I only want to have isolated black
> cases.
>
> The most surprising is that
> ?- genereMC([0, 0, 0, 97, 98, 99, 0, 0, 0]).
> answers NO !!!
>
> Where is my mistake ? (I use SWI-Prolog)
>
> I give you my code (NB : I'm french) :
> 'liste_francais_3.txt' contains a list of words like that :
> mot("abc").
> mot("adn").
> mot("afp").
> mot("age").
> mot("age").
> mot("agi").
> mot("ah").
> etc....
>
> --------------------------------------------------------------------------
--
> ------------------
>
> /* Charge la liste de mots */
>
> ?-consult('liste_francais_3.txt').
>
>
> /*------------------------------------------------------------------------
--
> ----*/
> /*---------------------------
> verifLigne ---------------------------------------*/
> /*------------------------------------------------------------------------
--
> ----*/
>
> /* Cas de l'appel de la fonction (2e parametre par défaut = [])  */
> verifLigne(L) :- verifLigne(L, []).
>
> /* Quand on arrive au bout de la ligne */
> verifLigne([], []).
> verifLigne([], MotCourant) :- mot(MotCourant).
>
> /* Quand on rencontre "un carré noir" */
> verifLigne([0], []).
> verifLigne([0], MotCourant) :- mot(MotCourant).
> verifLigne([0|[X|R]], []) :- X\==0, verifLigne([X|R], []).
> verifLigne([0|[X|R]], MotCourant) :- X\==0, mot(MotCourant),
> verifLigne([X|R], []).
>
> /* Cas général */
> verifLigne([X|R], MotCourant) :- X\==0, append(MotCourant, [X],
> NewMotCourant), verifLigne(R, NewMotCourant).
>
>
> /*pasDeLettresIsolees(MC).*/
>
>
> verifMotCroise([A,B,C,D,E,F,G,H,I]) :- verifLigne([A,B,C]),
> verifLigne([D,E,F]), verifLigne([G,H,I]),
>
> verifLigne([A,D,G]), verifLigne([B,E,H]), verifLigne([C,F,I]).
>
> affich([A,B,C,D,E,F,G,H,I]) :- name(L1, [A,B,C]), name(L2, [D,E,F]),
> name(L3, [G,H,I]), write(L1), nl, write(L2),
>
> nl, write(L3), nl.
>
> genereMC(L) :- verifMotCroise(L), affich(L).
>
>

"David Vago" <vd419ll@freemail.hu> a écrit dans le message de
news:ckmoog$5sf$1@namru.matavnet.hu...
> Hi!
>
> The reason you get multiple black squares is that when the
> variable X is not instantiated, the X \== 0 expression will be
> true, but that does not mean, that when X becomes instantiated,
> it cannot take the value 0.
> That is why genereMC/1 generates invalid crossword puzzles, however
> when all variables are instantiated at the beginning (calling the
predicate
> with the [0,0,0,97,98,99,0,0,0] argument), it will correctly recognize
> that is is an invalid puzzle.

OK, thank you very much for these explanations... I was suspecting the
"X\==0" but I couldn't be sure... I just a beginner !

> Here is how I would generate (and test) the validity of lines of puzzle
>
> % La ligne commence avec un carre noir
> verifLigne([0|L]) :- verifLigne2(L).
>
> % La ligne ne commence pas avec un carre noir
> verifLigne(L) :- verifLigne2(L).
>
> % Cas #1) Fin de la ligne.
> verifLigne2([]) :- !.
>
> % Cas #2) Tout le reste est un mot.
> verifLigne2(L) :- mot(L).
>
> % Cas #3) Il y a un mot, suivant par un carre noir, est des autres mots.
> verifLigne2(L) :- append(M, [0|L2], L), mot(M), verifLigne2(L2).

Thank you ! It works fine !!!!

> Sorry for my French, I haven't used it for a long time.

I can say the same with my english ! And your french is quite good !

Thank you.
Spoofix.