Ryuhei Miyashiro

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This paper concerns the method of selecting the best subset of explanatory variables in a multiple linear regression model. To evaluate a subset regression model, some goodness-of-fit measures, e.g., adjusted R, AIC and BIC, are generally employed. Although variable selection is usually handled via a stepwise regression method, the method does not always(More)
In sports timetabling, finding feasible pattern sets for a round robin tournament is a significant problem. Although this problem has been tackled in several ways, good characterization of feasible pattern sets is not known yet. In this paper, we consider the feasibility of a pattern set, and propose a necessary condition for feasible pattern sets. In the(More)
This paper deals with the break minimization problem of sports scheduling. The problem is to find a stadium assignment that minimizes the total number of breaks under a given round-robin tournament schedule. We show that the problem can be formulated as MAX RES CUT and MAX 2SAT. We also apply Goemans and Williamson’s approximation algorithm based on(More)
We propose a polynomial-time algorithm to find an equitable home–away assignment for a given timetable of a round-robin tournament. Our results give an answer to a problem raised by Elf et al. (Oper. Res. Lett. 31 (2003) 343), which concerns the computational complexity of the break minimization problem in sports timetabling. © 2004 Elsevier B.V. All rights(More)
The break minimization problem is to find a home-away assignment that minimizes the number of breaks for a given schedule of a round-robin tournament. In a recent paper, Elf et al. conjectured that this minimization problem is solvable in polynomial time if the optimal value of a given instance is less than the number of teams of the instance. We prove(More)
This paper describes the traveling tournament problem, a well-known benchmark problem in the field of tournament timetabling. We propose an approximation algorithm for the traveling tournament problem with the constraints such that both the number of consecutive away games and that of consecutive home games are at most k. When k≤5, the approximation ratio(More)
This paper deals with the traveling tournament problem, which is a well-known benchmark problem in the field of tournament timetabling. We propose a new lower bound for the traveling tournament problem, and construct a randomized approximation algorithm yielding a feasible solution whose approximation ratio is less than 2+(9/4)/(n−1), where n is the number(More)
A 2.75-approximation algorithm is proposed for the unconstrained traveling tournament problem, which is a variant of the traveling tournament problem. For the unconstrained traveling tournament problem, this is the first proposal of an approximation algorithm with a constant approximation ratio. In addition, the proposed algorithm yields a solution that(More)
OBJECTIVES The frequency and magnitude of depictions of risky events and unintentional injuries in top ranked children's animated and live action television programs was assessed. METHODS Qualitative and quantitative media content analysis were used. Scenes from television episodes were examined for the depiction of risky events and unintentional(More)
In this abstract, we deal with the Constant Distance Traveling Tournament Problem (CDTTP) [4], which is a special class of the Traveling Tournament Problem (TTP), established by Easton, Nemhauser and Trick [1]. We propose a lower bound of the optimal value of CDTTP, and two algorithms that produce feasible solutions whose objective values are close to the(More)