text: You've got me... By definition they would have to be positive integers.  So the absolute value of -y, would just be y...\n\nIf they are all prime, how can you represent z as the product of two other primes?  That contradicts your assertion that they are all primes.\n\nThe only way to make this work is to allow 1 to be considered a 'prime' number, but with current definitions of prime, this is not the case, nor can 0 be considered prime...\n\nOr if these are supposed to be the difference of factorials, there's another problem.  Every factorial of a prime (2! or above), will have 2 as a factor.  When you subtract two even numbers, the result is always even.  So the only way be if x! and y! were within 2 of each other.  Using the smallest primes possible (3! and 2!) you have 6 - 2 = 4, which is not 2.\n\nPlease explain what I'm missing...