Koji M. Kobayashi

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The bin packing problem has been extensively studied and numerous variants have been considered. The k-item bin packing problem is one of the variants introduced by Krause et al. in Journal of the ACM 22(4). In addition to the formulation of the classical bin packing problem, this problem imposes a cardinality constraint that the number of items packed into(More)
The online buffer management problem formulates the problem of queuing policies of network switches supporting QoS (Quality of Service) guarantee. We focus on multi-queue switches in QoS networks proposed by Azar et al. They introduced so-called "the relaxed model". Also, they showed that if the competitive ratio of the single-queue model is at most(More)
Recently, the problems of evaluating performances of switches and routers has been formulated as online problems, and a great amount of results have been presented. In this paper, we focus on managing outgoing packets (called egress traffic) on QoS (Quality of Service) switches, and analyze the performance of one of the most fundamental scheduling policies(More)
The online buffer management problem formulates the problem of queueing policies of network switches supporting QoS (Quality of Service) guarantee. For this problem, several models are considered. In this paper, we focus on shared memory switches with preemption. We prove that the competitive ratio of the Longest Queue Drop (<i>LQD</i>) policy is(More)
Kierstead and Trotter (Congressus Numerantium 33, 1981) proved that their algorithm is an optimal online algorithm for the online interval coloring problem. In this paper, for online unit interval coloring, we show that the number of colors used by the Kierstead-Trotter algorithm is at most 3ω(G) − 3, where ω(G) is the size of the maximum clique in a given(More)
BACKGROUND Massive gastrointestinal bleeding in children, mostly caused by esophageal varices secondary to chronic liver disease, is uncommon. Dieulafoy lesion in the gastrointestinal tract is a rare but important cause of gastrointestinal bleeding; massive bleeding from this lesion can be fatal unless adequate treatment is promptly initiated. We report a(More)