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\((S_2)\)-condition and Cohen-Macaulay binomial edge ideals. (English) Zbl 1512.05413

Summary: We describe the simplicial complex \(\Delta\) such that the initial ideal of the binomial edge ideal \(J_{\mathrm{G}}\) of \(G\) is the Stanley-Reisner ideal of \(\Delta\). By using \(\Delta\) we show that if \(J_G\) is \((S_2)\), then \(G\) is accessible. We also characterize all accessible blocks with whiskers of cycle rank 3 and we define a new infinite class of accessible blocks with whiskers for any cycle rank. Finally, by using a computational approach, we show that the graphs with at most 12 vertices whose binomial edge ideal is Cohen-Macaulay are all and only the accessible ones.

MSC:

05E40 Combinatorial aspects of commutative algebra
13C14 Cohen-Macaulay modules
13C05 Structure, classification theorems for modules and ideals in commutative rings
05C25 Graphs and abstract algebra (groups, rings, fields, etc.)
13F55 Commutative rings defined by monomial ideals; Stanley-Reisner face rings; simplicial complexes

Software:

nauty

References:

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