Nonderogatory directed windmills Molinos de viento dirigidos no derogatorios
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چکیده
Abstract. A directed graph G is nonderogatory if its adjacency matrix A is nonderogatory, i.e., the characteristic polynomial of A is equal to the minimal polynomial of A. Given integers r ≥ 2 and h ≥ 3, a directed windmill Mh (r) is a directed graph obtained by coalescing r dicycles of length h in one vertex. In this article we solve a conjecture proposed by Gan and Koo ([3]): Mh (r) is nonderogatory if and only if r = 2.
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تاریخ انتشار 2008