Please give a a reason, why 1 is a composite

tg at tg at
Wed Mar 25 19:20:26 UTC 2015

Vincent Lefevre <vincent at> writes:

  On 2015-03-25 08:45:53 +0100, tg at wrote:
  > There are texts (older ones more than modern ones) that define 1 to be
  > prime.  The common view today is that it is not prime (and certainly not
  > a composite).
  I agree, but this is not what the GMP 6.0.0 manual says:
   -- Function: int mpz_probab_prime_p (const mpz_t N, int REPS)
       Determine whether N is prime.  Return 2 if N is definitely prime,
       return 1 if N is probably prime (without being certain), or return
       0 if N is definitely composite.
  which implies that a number is either prime or composite. This is wrong!

Will do 's;composite;non-prime;'.

Please encrypt, key id 0xC8601622

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