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Feb 25, 2018 at 12:27 history edited Adam Przeździecki CC BY-SA 3.0
one "\" too many
Oct 11, 2012 at 15:26 comment added Will Traves @Fernando: Can't we view the set of completely reducible homogeneous polynomials of degree n in d variables as the image of the multiplication map sending (P(S1))n to P(Sn), where S=C[x0,…,xd−1]? The image of this morphism should be a projective subvariety of P(Sn), in particular it is a Zariski-closed set. The affine cone over this subvariety gives the affine variety that Jeurgen described.
Oct 11, 2012 at 2:26 vote accept Mark C. Wilson
Oct 11, 2012 at 2:27
Oct 10, 2012 at 23:01 comment added Fernando Muro This answer may be incorrect. The equations $F_\mu=0$ describe the Zariski closure of the sets of polynomials which factor as a product of linear factors, but nothing guarantees that this set is Zariski closed. It is of course constructible for the Zariski topology, since it is the image of a map between affine schemes (this is essentially what you show in your answer), but I don't see why it should be Zariski closed. BTW, Gröbner bases are a tool to compute the elimination ideal, which is simply an intersection, but conceptually they are unnecessary.
Oct 10, 2012 at 22:38 history answered Jürgen Böhm CC BY-SA 3.0