Prolog Program To Check If A Number Is Prime

Question

I wrote the following program based on the logic that a prime number is only divisible by 1 and itself. So I just go through the process of dividing it to all numbers that a

Answer 1

This answer is a follow-up to @lefunction's previous answer.

isPrime2/1 is as close as possible to isPrime1/1 with a few changes (highlighted below):

isPrime2(2) :-
    !.
isPrime2(3) :-
    !.
isPrime2(X) :-
    X > 3,
    X mod 2 =\= 0,
    isPrime2_(X, 3).

isPrime2_(X, N) :-
    (  N*N > X
    -> true
    ;  X mod N =\= 0,
       M is N + 2,
       isPrime2_(X, M)
    ).
    

Let's query!

?- time(isPrime1(99999989)).
% 24,999,999 inferences, 3.900 CPU in 3.948 seconds (99% CPU, 6410011 Lips)
true.

?- time(isPrime2(99999989)).
% 5,003 inferences, 0.001 CPU in 0.001 seconds (89% CPU, 6447165 Lips)
true.