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arXiv · 0909.4717

Binomial edge ideals and conditional independence statements

Juergen Herzog·Takayuki Hibi·Freyja Hreinsdottir·Thomas Kahle·Johannes Rauh
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Abstract

We introduce binomial edge ideals attached to a simple graph $G$ and study their algebraic properties. We characterize those graphs for which the quadratic generators form a Gröbner basis in a lexicographic order induced by a vertex labeling. Such graphs are chordal and claw-free. We give a reduced squarefree Gröbner basis for general $G$. It follows that all binomial edge ideals are radical ideals. Their minimal primes can be characterized by particular subsets of the vertices of $G$. We provide sufficient conditions for Cohen--Macaulayness for closed and nonclosed graphs. Binomial edge ideals arise naturally in the study of conditional independence ideals. Our results apply for the class of conditional independence ideals where a fixed binary variable is independent of a collection of other variables, given the remaining ones. In this case the primary decomposition has a natural statistical interpretation

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Juergen Herzog, Takayuki Hibi, Freyja Hreinsdottir, Thomas Kahle, Johannes Rauh. 2009-10-16. Binomial edge ideals and conditional independence statements. https://arxiv.org/abs/0909.4717

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