I suppose you could call a poly "prime" if it has no such decomposition. (And I use the term literally: "de-composition.") New kind of primeness notion. Seems to me Macsyma et al ought to offer finding this decomposition as yet another capability. Could be useful. If Landau does it over finite fields then doing it over integers (and perhaps rationals?) could be done via some kind of chinese remaindering of finite field results. In a finite field, there is a problem however. Some polynomial decomposition F(x)=G(H(x)) could happen, even though H and/or G actually have greater degree than F. Right? Can Landau detect those? Doubt it. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)