Research Interests:
In many applications of coalition formation games, a key issue is that some desirable coalition structures are not elements of the core of these games. In these cases, it would be useful for an authority which aims to implement a certain... more
In many applications of coalition formation games, a key issue is that some desirable coalition structures are not elements of the core of these games. In these cases, it would be useful for an authority which aims to implement a certain outcome to know how far from the original game is the nearest game where the desirable outcome is part of the core. This question is at the center of this study. Focusing on hedonic games, we uncover previously unexplored links between such games and transferrable utility games, and develop a tailor-made so- lution concept for the transferrable utility game, the implementation core, to provide an answer to our question.
Research Interests:
リサーチレポート（北陸先端科学技術大学院大学情報科学研究科）本文は図書館に配架されています。 / This material is stored in the JAIST library
Research Interests:
Research Interests:
ABSTRACT We are concerned with a fair division problem in which the indivisible “goods” to be distributed among a finite number of individuals have divisible “bads” associated with them. The problem is formulated and analyzed in terms of... more
ABSTRACT We are concerned with a fair division problem in which the indivisible “goods” to be distributed among a finite number of individuals have divisible “bads” associated with them. The problem is formulated and analyzed in terms of the housemates problem. We present an efficient procedure that decides whether an envy-free solution exists, and if so, finds one of them; otherwise finds a solution such that each envious housemate is assigned a room whose rent is zero. Copyright Springer-Verlag 2004
Research Interests:
Research Interests:
Abstract: The problem of minimizing the duration of a project is studied in situationsinvolving alternative activities of positive duration. A strongly polynomialDijkstra-type algorithm for solving the problem is proposed and analyzed.... more
Abstract: The problem of minimizing the duration of a project is studied in situationsinvolving alternative activities of positive duration. A strongly polynomialDijkstra-type algorithm for solving the problem is proposed and analyzed. Thealgorithm is applicable to projects in which an activity can be started only aftera prescribed number of immediately preceding activities have been selected andperformed. The underlying project network is not required to be acyclic. Moreover,inapplicability of the ...
Research Interests:
Research Interests:
This paper discusses the generalized mutual exclusion problem defined by H. Kakugawa and M. Yamashita. A set of processes shares a set of resources of an identical type. Each resource must be accessed by at most one process at any time.... more
This paper discusses the generalized mutual exclusion problem defined by H. Kakugawa and M. Yamashita. A set of processes shares a set of resources of an identical type. Each resource must be accessed by at most one process at any time. Each process may have different accessible resources. If two processes have no common accessible resource, it is reasonable to ensure a condition in resource allocation, which is called allocation independence in this paper, i.e., resource allocation to those processes must be performed without any interference. In this paper, we define a new structure, sharing structure coterie. By using a sharing structure coterie, the resource allocation algorithm proposed by H. Kakugawa and M. Yamashita ensures the above condition. We show a necessary and sufficient condition of the existence of a sharing structure coterie. The decision of the existence of a sharing structure coterie for an arbitrary distributed system is NP-complete. Furthermore, we show a resou...
Research Interests:
Top responsiveness was shown by Alcalde and Revilla [1] to guarantee the existence of core stable partitions in hedonic coalition formation games. In this paper we prove the existence of Nash stable partitions under top responsiveness... more
Top responsiveness was shown by Alcalde and Revilla [1] to guarantee the existence of core stable partitions in hedonic coalition formation games. In this paper we prove the existence of Nash stable partitions under top responsiveness when a mutuality condition is imposed.
Research Interests:
Research Interests:
Top responsiveness is introduced by Alcalde and Revilla [Journal of Mathematical Economics 40 (2004) 869-887] as a property which induces a rich domain on players's preferences in hedonic games, and guarantees the existence of core... more
Top responsiveness is introduced by Alcalde and Revilla [Journal of Mathematical Economics 40 (2004) 869-887] as a property which induces a rich domain on players's preferences in hedonic games, and guarantees the existence of core stable partitions. We strengthen this observation by proving the existence of strict core stable partitions, and when a mutuality condition is imposed as well, the existence of Nash stable partitions.
Research Interests:
In the real world, many infrastructures, for example, the internet, power/water supply and traffics, are network systems where high reliability is required. Independently, these systems may need costs for the construction or maintenance... more
In the real world, many infrastructures, for example, the internet, power/water supply and traffics, are network systems where high reliability is required. Independently, these systems may need costs for the construction or maintenance of components. In this study, we consider a bi-objective network with objectives of maximizing all-terminal reliabilities and minimizing costs. In general, there is trade-off relation between reliability and cost, and these objectives cannot be optimized simultaneously. Therefore, solving the problem is to find the set of Pareto solutions. However, evaluating all-terminal reliability of a given network is computationally intractable, which means that this bi-objective problem is also computationally intractable Therefore, previous study provided a Genetic Algorithm (GA) obtaining a set of quasi-Pareto solutions. However, this algorithm needed much computing time when the number of nodes was large. In this study, we improve the previous GA algorithm. ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
We mainly consider the complexity of negation-limited inverters. We show an upper bound $d+$ $3\lceil\log(n+1)\rceil$ on depth for negation-limited inverter whose size is $O(ns+n^{2})$ , where $d$ and $s$ is, respectively, the depth and... more
We mainly consider the complexity of negation-limited inverters. We show an upper bound $d+$ $3\lceil\log(n+1)\rceil$ on depth for negation-limited inverter whose size is $O(ns+n^{2})$ , where $d$ and $s$ is, respectively, the depth and the size of a monotone sorting network with optimal depth. If the optimal depth of monotone circuit for the majority function is not less than that for any other threshold function, this upper bound match the lower bound [11] and a superlinear lower bound $\Omega(n\log n)$ on size of depth-optimal negation-limited inverter on basis {AND, OR, NAND, NOR} is shown.
We are concerned with a model of network formation games, called local connection games, in which networks are formed based on players’ strategies. Each player may decide to build links to other players by paying a certain cost fixed in... more
We are concerned with a model of network formation games, called local connection games, in which networks are formed based on players’ strategies. Each player may decide to build links to other players by paying a certain cost fixed in advance, and a strategy of each player is a selection of links to be built. Each player determines and/or changes her or his strategy depending on cost for building links and cost of contacting all other players on the entire network, which influence the structure of the entire network. One of the main interests on the study of local connection games is to characterize all the stable strategy profiles. In this paper, we analyze the influences on network structure of stable strategy profiles caused by the cost for building links. For the unit cost case, we provide, in terms of network structure, a necessary and sufficient condition for strategy profiles to be stable. Moreover, we investigate the relationship between integral cost cases and non-integra...
Research Interests:
ABSTRACT We are dealing with the problem of maximizing the weighted number of pseudo just-in-time jobs on single machine model. The concept of pseudo just-in-time is a relaxation of just-in-time. In our formulation, each job is associated... more
ABSTRACT We are dealing with the problem of maximizing the weighted number of pseudo just-in-time jobs on single machine model. The concept of pseudo just-in-time is a relaxation of just-in-time. In our formulation, each job is associated with a time-window instead of due date, and the lengths of all such time-windows are bounded above by a certain value given in advanced. A job is called pseudo just-in-time if it is completed within its time-window. We show that the problem is polynomial time solvable, and moreover, we show some results on computational complexity for more general settings.
We consider the complexity of negation-limited inverters, circuits each of which inverts n input variables with only ⌈log(n+1)⌉ negation gates. We improve the upper bound on the depth and the lower bound on the size of negation-limited... more
We consider the complexity of negation-limited inverters, circuits each of which inverts n input variables with only ⌈log(n+1)⌉ negation gates. We improve the upper bound on the depth and the lower bound on the size of negation-limited inverters. Moreover, we give a superlinear lower bound Ω(nlogn) on the size of minimum-depth negation-limited inverters. As far as we know, this is the first superlinear lower bound on the size of non-monotone circuits with a weak depth restriction O(logn).
From a theorem of Markov, the minimum number of negation gates in a circuit su#cient to compute any collection of Boolean functions on n variable is # = + 1)#. Santha and Wilson [SIAM Journal of Computing 22(2):294--302 (1993)] showed... more
From a theorem of Markov, the minimum number of negation gates in a circuit su#cient to compute any collection of Boolean functions on n variable is # = + 1)#. Santha and Wilson [SIAM Journal of Computing 22(2):294--302 (1993)] showed that in some classes of bounded-depth circuits # negation gates are no longer su#cient for some explicitly defined Boolean function. In this paper, we consider a general class of bounded-depth circuits in which each gate computes an arbitrary monotone Boolean function or its negation. Our purpose is to extend the theorem of Markov for such a general class of circuits. We first show that a lower bound shown by Santha and Wilson becomes an extension of Markov's lower bound by a small refinement. Then, we present tight upper bounds on the number of negations for computing an arbitrary collection of Boolean functions.
ABSTRACT Top responsiveness is a concept which provides a model of progressive society in wihch each player pays more attention to the best aspect of each coalition, and is shown to be a sufficient conditaion for the existence of core... more
ABSTRACT Top responsiveness is a concept which provides a model of progressive society in wihch each player pays more attention to the best aspect of each coalition, and is shown to be a sufficient conditaion for the existence of core stable coalition structures. In this paper, we propose a new concept, called bottom refuseness, for modeling societies with conservative players, i.e., each player pays more attention to the worst aspect of each coalition, and has tendency to choose among options a safer one. We show that all hedonic games satisfying bottom refuseness have core stable coalition structures. Moreover, we show that some previous results can be shown when additivity is imposed on top responsiveness and bottom refuseness.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
In this paper, we propose game theoretical models for developing staffing strategies, i.e., strategies which support managers’ decision making on hiring, head hunting, staff reassignment, and implementation of staff development policy in... more
In this paper, we propose game theoretical models for developing staffing strategies, i.e., strategies which support managers’ decision making on hiring, head hunting, staff reassignment, and implementation of staff development policy in enterprises. Our staffing models are hedonic coalition formation games with newly proposed stability concepts called invitation based stabilities, in which players’ activities of changing their coalitions are motivated based on invitation from other coalitions. These stabilities capture behaviors of managers, employees, and contractors depending on the balance of power in business situations. We analyze the existence of stable coalition structures under invitation based stabilities, and provide several sufficient conditions with natural interpretations as staffing strategies.
Research Interests:
Research Interests:
Top responsiveness is introduced by Alcalde and Revilla [Journal of Mathematical Economics 40 (2004) 869-887] as a property which induces a rich domain on playerss preferences in hedonic games, and guarantees the existence of core stable... more
Top responsiveness is introduced by Alcalde and Revilla [Journal of Mathematical Economics 40 (2004) 869-887] as a property which induces a rich domain on playerss preferences in hedonic games, and guarantees the existence of core stable partitions. We strengthen this observation by proving the existence of strict core stable partitions, and when a mutuality condition is imposed as well, the
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT Parallelization methods on a condition are proposed for three types of quantum circuits, where the condition is that the number of available ancillae is limited and parallelization means that a given quantum circuit is... more
ABSTRACT Parallelization methods on a condition are proposed for three types of quantum circuits, where the condition is that the number of available ancillae is limited and parallelization means that a given quantum circuit is reconstructed as one with smaller depth. As a by-product, for the three types of n-input quantum circuits, upper bounds on the number of ancillae for parallelizing to logarithmic depth are reduced to 1/logn of the previous upper bounds.