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Exposed circuits, linear quotients, and chordal clutters. (arXiv:1812.08128v1 [math.CO])
来源于:arXiv
A graph $G$ is said to be chordal if it has no induced cycles of length four
or more. In a recent preprint Culbertson, Guralnik, and Stiller give a new
characterization of chordal graphs in terms of sequences of what they call
`edge-erasures'. In this note we show that these moves are in fact equivalent
to a linear quotient ordering on $I_{\overline{G}}$, the edge ideal of the
complement graph $\overline G$. Known results imply that $I_{\overline G}$ has
linear quotients if and only if $G$ is chordal, and hence this recovers an
algebraic proof of their characterization. We investigate higher-dimensional
analogues of this result, and show that in fact linear quotients for more
general circuit ideals of $d$-clutters can be characterized in terms of
removing exposed circuits in the complement clutter. Restricting to properly
exposed circuits can be characterized by a homological condition. This leads to
a notion of higher dimensional chordal clutters which borrows from commutative
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