CUT.pl

% In Prolog, the cut (!) is a control construct used to commit to the choices made during the execution of a program. 
% It prunes the search space and prevents backtracking to choices made before the cut. 
% The cut is a powerful tool, but it should be used with caution, as it can make the code less readable and harder to understand.

% Here's a simple example to illustrate the use of the cut:

/* Define a predicate to classify a number as positive, negative, or zero */
classify_number(X, positive) :- X > 0, !.
classify_number(X, zero)     :- X =:= 0, !.
classify_number(X, negative) :- X < 0.

/* Example usage */
?- classify_number(5, Class).
% Output: Class = positive

?- classify_number(0, Class).
% Output: Class = zero

?- classify_number(-3, Class).
% Output: Class = negative
% End

% The cut (!) and the fail/0 predicate are often used together to control backtracking and terminate search branches.
% The fail/0 predicate awlays fails, and when combined with the cut, it can be used to prune certain paths. 

% Here's an example to illustrate the use of cut and fail:
/* Define a predicate to find the first positive element in a list */
first_positive([X|_], X) :- X > 0, !.
first_positive([_|Tail], Result) :- first_positive(Tail, Result).
first_positive([], no_positive).

/* Example usage */
?- first_positive([1, -2, 3, -4, 5], Result).
% Output: Result = 1

?- first_positive([-1, -2, -3], Result).
% Output: Result = no_positive
% End