Resumen
Let C be a clutter and let A be its incidence matrix. If the linear system x ≥ 0; x A ≤ 1 has the integer rounding property, we give a description of the canonical module and the a-invariant of certain normal subrings associated to C. If the clutter is a connected graph, we describe when the aforementioned linear system has the integer rounding property in combinatorial and algebraic terms using graph theory and the theory of Rees algebras. As a consequence we show that the extended Rees algebra of the edge ideal of a bipartite graph is Gorenstein if and only if the graph is unmixed.
Idioma original | Inglés |
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Páginas (desde-hasta) | 801-811 |
Número de páginas | 11 |
Publicación | Anais da Academia Brasileira de Ciencias |
Volumen | 82 |
N.º | 4 |
DOI | |
Estado | Publicada - 2010 |