Editing Bateman–Horn conjecture (section)

==Negative numbers==
As stated above, the conjecture is not true: the single polynomial ''ƒ''<sub>1</sub>(''x'')&nbsp;=&nbsp;&minus;''x'' produces only negative numbers when given a positive argument, so the fraction of prime numbers among its values is always zero. There are two equally valid ways of refining the conjecture to avoid this difficulty:
*One may require all the polynomials to have positive leading coefficients, so that only a constant number of their values can be negative.
*Alternatively, one may allow negative leading coefficients but count a negative number as being prime when its absolute value is prime.
It is reasonable to allow negative numbers to count as primes as a step towards formulating more general conjectures that apply to other systems of numbers than the integers, but at the same time it is easy
to just negate the polynomials if necessary to  reduce to the case where the leading coefficients are positive.