Quote:
Originally Posted by ATH
Will P+1 test in GMPECM also find P1 smooth factors?

Yes.
Quote:
Originally Posted by ATH
If yes will P1 smooth factors only be found by half the seeds x0 same as P+1 smooth factors? (In a P+1 test).

Yes.
Suppose a number N has two smooth prime factors f and g (and other not smooth prime factors, which we don't care about). f is + side smooth, g is  side smooth (i.e. f+1 and g1 are smooth to given b1/b2 bounds)
Then there exist seeds such that:
1) they will find both f & g when doing a P+1 run to b1/b2 bounds
2) they will find f but not g ...
3) they will find g but not f ...
4) they will find neither f nor g ...
Whether a given seed will find a given factor depends on both the relationship of the seed to the factor and the smoothness side of the factor. As long as they "align", the factor will be found. Probability of alignment is 50%, regardless of whether the smooth side is +1 or 1.