• DOI:10.1090/S0002-9939-2010-10416-1
• Corpus ID: 4971435

Affine toric equivalence relations are effective

@inproceedings{Raicu2009AffineTE,
  title={Affine toric equivalence relations are effective},
  author={Claudiu Raicu},
  year={2009}
}

• Claudiu Raicu
• Published 29 May 2009
• Mathematics

Any map of schemes defines an equivalence relation , the relation of ``being in the same fiber''. We have shown elsewhere that not every equivalence relation has this form, even if it is assumed to be finite. By contrast, we prove here that every toric equivalence relation on an affine toric variety does come from a morphism and that quotients by finite toric equivalence relations always exist in the affine case. In special cases, this result is a consequence of the vanishing of the first cohomology group in the Amitsur complex associated to a toric map of toric algebras. We prove more generally the exactness of the Amitsur complex for maps of commutative monoid rings.