Coalition structure generation in cooperative games with compact representations

This paper presents a new way of formalizing the coalition structure generation problem (CSG) so that we can apply constraint optimization techniques to it. Forming effective coalitions is a major research challenge in AI and multi-agent systems. CSG involves partitioning a set of agents into coalitions to maximize social surplus. Traditionally, the input of the CSG problem is a black-box function called a characteristic function, which takes a coalition as input and returns the value of the coalition. As a result, applying constraint optimization techniques to this problem has been infeasible. However, characteristic functions that appear in practice often can be represented concisely by a set of rules, rather than treating the function as a black box. Then we can solve the CSG problem more efficiently by directly applying constraint optimization techniques to this compact representation. We present new formalizations of the CSG problem by utilizing recently developed compact representation schemes for characteristic functions. We first characterize the complexity of CSG under these representation schemes. In this context, the complexity is driven more by the number of rules than by the number of agents. As an initial step toward developing efficient constraint optimization algorithms for solving the CSG problem, we also develop mixed integer programming formulations and show that an off-the-shelf optimization package can perform reasonably well

生体鉱化作用における非晶質炭酸カルシウム(ACC)の研究

学位の種別:課程博士University of Tokyo(東京大学

Quantum critical behavior of the hyperkagome magnet Mn3CoSi

β-Mn-type family alloys Mn3TX (T = Co, Rh, and Ir; X = Si and Ge) have a three-dimensional antiferromagnetic (AF) corner-shared triangular network, i.e., the hyperkagome lattice. The antiferromagnet Mn3RhSi shows magnetic short-range order over a wide temperature range of approximately 500 K above the Néel temperature TN of 190 K. In this family of compounds, as the lattice parameter decreases, the long-range magnetic ordering temperature decreases. Mn3CoSi has the smallest lattice parameter and the lowest TN in the family. The quantum critical point (QCP) from AF to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 Å. Although the Néel temperature of Mn3CoSi is only 140 K, the emergence of the quantum critical behavior in Mn3CoSi is discussed. We study how the magnetic short-range order appears in Mn3CoSi by using neutron scattering, μSR, and bulk characterization such as specific heat capacity. According to the results, the neutron scattering intensity of the magnetic short-range order in Mn3CoSi does not change much at low temperatures from that of Mn3RhSi, although the μSR short-range order temperature of Mn3CoSi is largely suppressed to 240 K from that of Mn3RhSi. Correspondingly, the volume fraction of the magnetic short-range order regions, as shown by the initial asymmetry drop ratio of μSR above TN, also becomes small. Instead, the electronic-specific heat coefficient γ of Mn3CoSi is the largest in this Mn3T Si system, possibly due to the low-energy spin fluctuation near the quantum critical point

敗血症における脂肪乳剤投与の意義に関する研究

本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである京都大学0048新制・課程博士医学博士甲第4869号医博第1293号新制||医||506(附属図書館)UT51-91-R407京都大学大学院医学研究科外科系専攻(主査)教授 前谷 俊三, 教授 小澤 和惠, 教授 戸部 隆吉学位規則第5条第1項該当Kyoto UniversityDFA

Identification of β-phenylalanine as a non-protein amino acid in cultivated rice, Oryza sativa

Non-protein amino acids, often analogs of the standard 20 protein amino acids, have been discovered in many plant species. Recent research with cultivated rice (Oryza sativa) identified (3R)-β-tyrosine, as well as a tyrosine amino mutase that synthesizes (3R)-β-tyrosine from the protein amino acid (2S)-α-tyrosine. Gas chromatography-mass spectrometry (GC-MS) assays and comparison to an authentic standard showed that β-phenylalanine is also a relatively abundant non-protein amino acid in rice leaves and that its biosynthesis occurs independently from that of β-tyrosine

Coalitional Games in Open Anonymous Environments

Coalition formation is a key aspect of automated negotiation among self-interested agents. In order for coalitions to be stable, a key question that must be answered is how the gains from cooperation are to be distributed. Various solution concepts (such as the Shapley value, core, least core, and nucleolus) have been proposed. In this paper, we demonstrate how these concepts are vulnerable to various kinds of manipulations in open anonymous environments such as the Internet

Alveolar echinococcosis of the liver in children

Background/purpose. Alveolar echinococcosis of the liver (AEL) is a zoonosis that is distributed in cold regions of the northern hemisphere. The disease is mostly found in adults and rarely in pediatric patients because it tends to be slow growing. Patients and methods. Ten Japanese pediatric patients with AEL (under fifteen-year-old) have been operated on in Hokkaido University Hospital from January 1936 to June 2008. We examined these children and revealed the characteristics of AEL. Results. The patients included three males and seven females whose mean age was 10.9 years old, ranging from 7 to 15. The length of follow-up was from 3 months to 33 years (median: 19 years). Six cases were picked up by mass screening and nine cases who underwent hepatectomy are still alive and one case whose tumors were unresectable died of liver failure. Conclusion. Our cases indicate that some AEL pediatric patients advanced rapidly, so early detection is imperative. Thus, screening examinations are essential for children in contaminated areas, and complete radical resection should be performed if a liver tumor is found on a screening examination and diagnosed as AEL