I have written the following program in SWI-Prolog:
male(reza).
male(aliakbar).
male(behrooz).
male(said).
male(aliasghar).
male(taghi).
male(gholamreza).
male(hadi).
female(fatema).
female(tahere).
female(olya).
female(fatema).
mother(fateme,reza).
mother(olya,hasan).
mother(x,y) :-
wife(x,z),
father(z,y).
brother(said,reza).
brother(x,y) :-
father(z,x),
father(z,y),
x\==y,
male(x).
sister(tahere,fateme).
sister(x,y) :-
father(z,x),
father(z,y),
x\==y,
female(x).
sister(olya,aliakbar).
wife(tahere,gholamreza).
father(gholamreza,hadi).
father(gholamreza, nastaran).
father(abdollah,hasan).
father(aliakbar,reza).
father(taghi,olya).
father(taghi,aliakbar).
father(taghi,aliasghar).
father(aliakbar,said).
grandfather(x,z) :-
father(x,y),
father(y,z).
grandfather(x,z) :-
father(x,y),
mother(y,z).
uncle(y,x) :-
father(z,x),
brother(z,y),
male(y).
aunt(y,x) :-
mother(z,x),
sister(z,y),
female(y).
cousin(y,x) :-
aunt(z,x),
mother(z,y),
female(y).
cousin(y,x) :-
aunt(z,x),
mother(z,y),
male(y).
When I consult "father(X,Y),father(Y,Z)." it returns the correct answer (names are in persian), i.e. it returns
X = taghi,
Y = aliakbar,
Z = reza ;
X = taghi,
Y = aliakbar,
Z = said ;
false.
But I could not find the correct answer of grandfather(X,Y). Please help me why.
Thanks.
Be careful: case is crucial in Prolog. Your rules cannot be interpreted right because you didn't use capitals for variables.
Related
defining IF like this :
dynamic(if/1).
op(200, fx, if).
op(150, xfx, then).
op(100, xfy, and).
op(100, xfy, or).
generates the following canonical form :
?- write_canonical(if x then y).
if(then(x,y))
?- write_canonical(if x and z then y).
if(then(and(x,z),y))
?- write_canonical(if x and z or t then y).
if(then(and(x,or(z,t)),y))
Is there a way to generate :
if( conds, then(actions) ).
OR even better :
if( conds, (actions) ).
like this :
if(x,y)
if(x, then(y))
if( and(x,or(z,t)), then(y))
if( and(x,or(z,t)), (y))
one possible alternative I can see :)
?- op(200, xfy, ==>).
?- write_canonical(x ==> y).
==>(x,y)
?- write_canonical(x and z ==> y).
==>(and(x,z),y)
I found better solution to generate normal clauses. Instead of "then" I can just use ":-"
?- write_canonical(if x and z :- y ).
:-(if(and(x,z)),y)
?- assert(if x and z :- write(axz) ).
?- if x and z.
axz
I am working on a family tree(Royal) implementation in prolog, and I am fairly new to prolog. So whenever I run:
| ?- brother_in_law(Who, diana).
Who = andrew ? ;
Who = andrew ? ;
Who = edward ? ;
Who = edward ? ;
no
As you can see, I'm getting these duplicates answers, and I was wondering if this is normal in prolog, or am I doing something wrong? How do I fix it? Any help would be appreciated.
This is my predicate for brother_in_law:
brother_in_law(B, X) :- male(B), brother(B, M), spouse(X, M).
Predicate for brother:
brother(X, Y) :- male(X), sibling(X, Y).
And final predicate siblings:
sibling(X, Y) :- child(X, P), child(Y, P), X \= Y.
Then I also have other facts such as male(edward), female(diana), and spouse(diana, charles), etc.
This is my prolog file.
male(bob).
male(john).
female(betty).
female(dana).
father(bob, john).
father(bob, dana).
mother(betty, john).
mother(betty, dana).
husband(X, Y) :- male(X), mother(Y, Z), father(X, Z).
wife(X, Y) :- female(X), father(Y, Z), mother(X, Z).
son(X, Y) :- male(X), mother(Y, X);female(X), father(Y, X).
daughter(X, Y) :- female(X), mother(Y, X);female(X), father(Y, X).
sister(X, Y) :- female(X), mother(Z, X), mother(Z, Y), X \= Y.
brother(X, Y) :- male(X), mother(Z, X), mother(Z, Y), X \= Y.
I want a name of rule if it returns true for any value x or y.
Let's say x = betty and y = john.
mother(betty, john). <- this will meet so my rule should return 'mother'.
Similarly if any other rule or fact meets true for some value x, y it should return that rule name.
How can I achieve something like that?
could be easy as
query_family(P1, P2, P) :-
% current_predicate(P/2),
member(P, [father, mother, husband, wife, son, daughter, sister, brother]),
call(P, P1, P2).
that gives
?- query_family(betty, john, R).
R = mother ;
false.
?- query_family(betty, X, R).
X = john,
R = mother ;
X = dana,
R = mother ;
X = bob,
R = wife ;
X = bob,
R = wife ;
false.
the semicolon after the answer means 'gimme next'
$ swipl
?- ['facts'].
?- setof( Functor,
Term^(member(Functor, [father, mother, husband, wife, son, daughter, sister, brother]),
Term =.. [Functor, betty, john],
once(Term)),
Answer).
Answer = [mother].
?-
If you want to avoid having to specify the list of functors of interest, you could use current_predicate(F/2).
I am struggling to get my head around this basic Prolog concept.
I understand that the basic clause for determining the ancestor of a person is as follows:
ancestor(X, Y) :- parent(X, Y).
ancestor(X, Y) :- parent(X, Z), ancestor(Z, Y).
However, I am trying to get my head around how this works for a prolog program that implements lists to determine children of a parent, i.e:
parent_of(simon, [matthew, andrea, joanne]).
To determine wether or not somebody is the father of somebody, I am using this which works perfectly:
father_of(X, Y) :- parent_of(X, List), my_member(Y, List), male(X).
However, I cant seem to figure out how to get this to work for the ancestor clause above.
member/2 it's the simpler relation between an element and a list:
ancestor_of(X, Y) :- parent_of(X, Ys), member(Y, Ys).
ancestor_of(X, Y) :- parent_of(X, Zs), member(Z, Zs), ancestor_of(Z, Y).
I've added a relation to test the transitive rule
parent_of(simon, [matthew, andrea, joanne]).
parent_of(andrea, [bill, joan]).
yields
?- ancestor_of(andrea,A).
A = bill ;
A = joan ;
false.
?- ancestor_of(simon,A).
A = matthew ;
A = andrea ;
A = joanne ;
A = bill ;
A = joan ;
false.
?- ancestor_of(X,bill).
X = andrea ;
X = simon ;
false.
A (very) strange story:
I married a widow(W) who has a daughter(D). My father(F) married my stepdaughter (D). My wife gave birth to a son(s1). The wife of my father (the stepdaughter) also had a son (s2).
The goal of this project is to input:
grandfather(i,i).
and return yes in prolog.
Here is what I have so far:
%facts
father(f,i).
husband(i,w).
husband(f,d).
mother(w,d).
mother(w,s1).
father(i,s1).
mother(d,s2).
father(f,s2).
%rules
father(X,Y) :- f_in_law(X,Y).
father(X,Y) :- husband(X,Z),mother(Z,Y).
f_in_law(X,Y) :- husband(Z,Y),father(X,Z).
b_in_law(X,Y) :- husband(Z,Y),brother(X,Z).
%brother(X,Y) :- b_in_law(X,Y).
uncle(X,Y) :- father(Z,Y),brother(X,Z).
grandfather(X,Y) :- father(Z,Y),father(X,Z).
I traced through it to see what went wrong. father(f,i) is true so that's good! But father(i,f) is thought of as false. Any suggestions/ideas on how to correct this? I appreciate any input as I am rather new to prolog.
Should the predicate be
f_in_law(X,Y) :- husband(Y,Z),father(X,Z).
instead of
f_in_law(X,Y) :- husband(Z,Y),father(X,Z).
I have reformulated the riddle
father(i, s1).
father(f, i).
father(f, s2).
fatlaw(X, Y) :- husband(X, Z), mother(Z, Y).
mother(w, d).
mother(w, s1).
mother(d, s2).
motlaw(X, Y) :- husband(Z, X), father(Z, Y).
husband(i, w).
husband(f, d).
grandfather(X, Y) :-
( father(X, Z) ; fatlaw(X, Z) )
, ( father(Z, Y) ; fatlaw(Z, Y) ; mother(Z, Y) ; motlaw(Z, Y) )
.
the point seems to be that grandfather must accept fake biological offsprings (I hope this is reasonable English).
with that
?- grandfather(X,X).
X = i ;
false.