Jan Draisma, Rob Eggermont, Robert Krone and Anton
Leykin
Vol. 9 (2015), No. 8, 1857–1880
DOI: 10.2140/ant.2015.9.1857
Abstract
We consider a large class of monomial maps respecting an action of the infinite
symmetric group, and prove that the toric ideals arising as their kernels are finitely
generated up to symmetry. Our class includes many important examples
where Noetherianity was recently proved or conjectured. In particular, our
results imply Hillar–Sullivant’s independent set theorem and settle several
finiteness conjectures due to Aschenbrenner, Martín del Campo, Hillar, and
Sullivant.
We introduce a
matching monoid and show that its monoid ring is Noetherian up
to symmetry. Our approach is then to factorize a more general equivariant monomial
map into two parts going through this monoid. The kernels of both parts are finitely
generated up to symmetry: recent work by Yamaguchi–Ogawa–Takemura on the
(generalized) Birkhoff model provides an explicit degree bound for the kernel of the
first part, while for the second part the finiteness follows from the Noetherianity of
the matching monoid ring.
Department of Mathematics and
Computer Science
Technische Universiteit Eindhoven
P.O. Box 513, 5600 MB Eindhoven
Netherlands Vrije Universiteit and Centrum voor Wiskunde en
Informatica
Amsterdam
Netherlands