View Single Post
Old 2008-03-22, 15:02   #2
(loop (#_fork))
fivemack's Avatar
Feb 2006
Cambridge, England

638310 Posts

I suppose I usually sieve over algebraic special-Q out of habit; if asked to justify myself, the algebraic side for GNFS jobs is generally much larger than the rational side, and I believe it makes sense to use the special-Q to render effectively smaller the numbers which started off largest, but that's not an answer for why I use -a pretty much universally in SNFS cases.

I haven't done the experiments to see how much duplication there is in a case with roughly equal-sized rational and algebraic side if you sieve on both sides; it might be sensible as a way to push yields up on SNFS problems with particularly intractable polynomials.
fivemack is offline   Reply With Quote