-- Dec 1 In-Class Exercise Thread
natural(0).
natural(N) :- natural(M), N is M+1.
divisible(X,Y) :- 0 is X mod Y, !.
divisible(X,Y) :- X > Y+1, divisible(X, Y+1).
isPrime(2) :- true,!.
isPrime(X) :- X < 2,!,false.
isPrime(X) :- not(divisible(X, 2)).
prime(100) :- natural(I),
isPrime(I), write(I), nl,
I = 97, !.
natural(0).
natural(N) :- natural(M), N is M+1.
divisible(X,Y) :- 0 is X mod Y, !.
divisible(X,Y) :- X > Y+1, divisible(X, Y+1).
isPrime(2) :- true,!.
isPrime(X) :- X < 2,!,false.
isPrime(X) :- not(divisible(X, 2)).
prime(100) :- natural(I),
isPrime(I), write(I), nl,
I = 97, !.