Prolog arithmetic syntax

Question

How to define a as a integer/float number ?

I want to find the results of a+b+c+d=10 where a,b,c,d is integer and >=0

Answer 1

Here is GNU-Prolog piece of code with constraint solving over finite domains :

$ gprolog
| ?- [user].
compiling user for byte code...
ten(A,B,C,D) :- fd_domain([A,B,C,D],0,9999999), 10 #= A + B + C + D.

Ctrl + D

| ?- ten(A,B,C,D), fd_labeling([A,B,C,D]).

As you can see, it solves problem of big ranges like 0-9999999

A = 0
B = 0
C = 0
D = 10 ? ;

A = 0
B = 0
C = 1
D = 9 ? ;

A = 0
B = 0
C = 2
D = 8 ? ;
...

P.S. Thanks for Przemysław Kobylański for his blog with clear, very nice Prolog examples, where I've found inspiring examples.

P.P.S. When playing with finite domains, you might like to use fd_set_vector_max/1 . In above case it's not needed, but depending on constraint might be usefull - more details when Gnu-Prolog operates on ranges, when on vectors of possible values, can be found at manual "Finite domain solver and built-in predicates - Introduction"