Variables type in Prolog

[Bl1nD]

How can you tell the program tha variable X is has a certin type ...

This is actually the problem ...

3. Define a predicate is_between(X , Y , N) meaning "N is between X and Y" and working like in the example below (there is a predefined PROLOG predicate called between that has the same behavior):
?- is_between(1,5,3).

Yes

?- is_between(1,5,7).

No

?- is_between(1,5,N).

N = 1 ;

N = 2 ;

N = 3 ;

N = 4 ;

N = 5 ;

No

ps: i'm a newbie .. if you didn't noticed

 

[pimi]

It may solve by this program.

is_between(X, Y, N) :-
X - 1 < Y,
N is X.

is_between(X, Y, N) :-
X - 1 < Y,
is_between(X + 1, Y, N).

example:

?- is_between(3, 11, 1).
no

?- is_between(3, 11, 3).
yes

?- is_between(3, 11, 7).
yes

?- is_between(3, 11, 11).
yes

?- is_between(3, 11, 15).
no

?- is_between(2, 4, N).
N = 2 ;
N = 3 ;
N = 4 ;
no

?- is_between(6, 6, N).
N = 6 ;
no

?- is_between(4, 2, N).
no