CODEWITHSUNDEEP
prolog
Jatin Khurana
Jatin Khurana

Reputation: 1175

what is the mean of \+ in the below code

I am analyzing the code of whether a number is prime or not i am not able to get the meaning of operator "\+" in prolog.(I am naive in prolog).

is_prime(2). is_prime(3).
is_prime(P) :- integer(P), P > 3, P mod 2 =\= 0, \+ has_factor(P,3).
has_factor(N,L) :- N mod L =:= 0.
has_factor(N,L) :- L * L < N, L2 is L + 2, has_factor(N,L2).

I have understand the other thing but not able to understand the meaning of "\+" in second line.

can anyone explain me the above?

Upvotes: 0

Views: 319

Answers (1)

chiastic-security
chiastic-security

Reputation: 20520

It means "not provable". So \+ Thing succeeds if Thing can't be proven.

There's a useful dictionary of Prolog. The negation section is what you're after.

Upvotes: 1

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