An anytime approximation method for the inverse Shapley value problem

Coalition formation is the process of bringing together two or more agents so as to achieve goals that individuals on their own cannot, or to achieve them more efficiently. Typically, in such situations, the agents have conflicting preferences over the set of possible joint goals. Thus, before the agents realize the benefits of cooperation, they must find a way of resolving these conflicts and reaching a consensus. In this context, cooperative game theory offers the voting game as a mechanism for agents to reach a consensus. It also offers the Shapley value as a way of measuring the influence or power a player has in determining the outcome of a voting game. Given this, the designer of a voting game wants to construct a game such that a players Shapley value is equal to some desired value. This is called the inverse Shapley value problem. Solving this problem is necessary, for instance, to ensure fairness in the players voting powers. However, from a computational perspective, finding a players Shapley value for a given game is #p-complete. Consequently, the problem of verifying that a voting game does indeed yield the required powers to the agents is also #P-complete. Therefore, in order to overcome this problem we present a computationally efficient approximation algorithm for solving the inverse problem. This method is based on the technique of successive approximations; it starts with some initial approximate solution and iteratively updates it such that after each iteration, the approximate gets closer to the required solution. This is an anytime algorithm and has time complexity polynomial in the number of players. We also analyze the performance of this method in terms of its approximation error and the rate of convergence of an initial solution to the required one. Specifically, we show that the former decreases after each iteration, and that the latter increases with the number of players and also with the initial approximation error. Copyright © 2008, International Foundation for Autonomous Agents and Multiagent Systems (www.ifaarnas.org). All rights reserved

On efficient procedures for multi-issue negotiation

This paper studies bilateral, multi-issue negotiation between self-interested agents with deadlines. There are a number of procedures for negotiating the issues and each of these gives a different outcome. Thus, a key problem is to decide which one to use. Given this, we study the three main alternatives: the package deal, the simultaneous procedure, and the sequential procedure. First, we determine equilibria for the case where each agent is uncertain about its opponent’s deadline. We then compare the outcomes for these procedures and determine the one that is optimal (in this case, the package deal is optimal for each party). We then compare the procedures in terms of their time complexity, the uniqueness and Pareto optimality of their solutions, and their time of agreement

Chitin/Chitosan’s Bio-Fertilizer: Usage in Vegetative Growth of Wheat and Potato Crops

This chapter consists of valuing the chitosan to create bio-fertilizers as fertilizers without going through the composting process because of their richness in the nutrient base elements of plants: nitrogen and phosphorus. Physicochemical analyses of the chitosan focused on pH, dry matter, organic matter, nitrogen, phosphorus and potassium as well as IR and XRD. The samples thus prepared were monitored for 15 days. PH, temperature and conductivity were monitored daily. According to the physicochemical analyses of waste (nitrogen, phosphorus and potassium) and the nutritional needs of our selected crop (soft wheat, Arrehane variety which are 90-90-50 U/ha), several doses are then determined for the purpose of the optimal formula after their application on the crop. An application of bio-fertilizer on the potato was also undertaken. Follow-ups were carried out during this study, such as the monitoring of the vegetative growth of wheat and the mineralization of the soil via its physicochemical analyses. The results show that our bio-fertilizer is rich in nitrogen with 4.98% and phosphorus with 1.42% and mineralizes quickly on the ground while leaving the soft wheat to absorb its nutrients effectively and improving its growth properties, then giving good yields

Assessment of Students Performances in Biology: Implication for Measurements and Evaluation of Learning

Scienceeducation is believed to be a vital tool for individual and societal development at large. The persistent low levels of students' achievement in sciences at the various public examinations in Nigeria have continued to draw the attention of major stakeholders in education. This study examined academic achievement of Senior Secondary School students in biology and gender difference in students' achievement was examined. Ex-post facto design of descriptive research was adopted for the study. A proforma was used to collect data from a sample of two hundred (200) students, selected using stratified random sampling procedure from the Science secondary schools in Kano state Nigeria. The data collected were the students' performances in biology achievement tests. The data were analysed using descriptive statistics and independent-sample t-test. Overall results showed that the test internal consistency reliability is low and unsatisfactory; the students performed below average (M=47.02, SD=16.493 (47%). Similarly, gender difference exists in biology performance with another significant difference between performance of urban and rural school students. The study concludes that, biology test used in Kano state qualifying examinations to assess students potential ability in biology is not a reliable measurement tool and that, academic performance of students in biology is unsatisfactory and evidence of differential performance between gender and schools locations. The implication for measurements and evaluation of learning as well as recommendations has been discussed

Needs, Attitudes Toward Seeking Professional Help, and Preferred Sources of Help Among Emirati College Students

This investigation, conducted in the United Arab Emirates (UAE), examined Emirati college students’ needs, help-seeking attitudes, preference for source of help, and perceptions of counseling services offered on campus. Most participants reported moderate levels of personal, academic, career, and interpersonal needs, although results varied along gender lines. Overall, participants displayed slightly positive attitudes toward seeking professional help, yet showed negative attitudes toward interpersonal openness, although this, too, differed by gender. Participants preferred non-professional sources of help, such as family and friends. Participants understood counseling services on campus to refer to academic-related services. Findings are discussed within the UAE cultural context

From Hashtags to Movements: A Framing Perspective of The Role of Social Media in the Emergence and Development of Impactful Social Movements

Social media plays a critical role in social movement activities. This study takes a framing perspective to investigate how social media affordances support the process of creation, communication, and negotiation of frames and assess the impact of the framing process on social movement outcomes

Acceptance conditions in automated negotiation

In every negotiation with a deadline, one of the negotiating parties has to accept an offer to avoid a break off. A break off is usually an undesirable outcome for both parties, therefore it is important that a negotiator employs a proficient mechanism to decide under which conditions to accept. When designing such conditions one is faced with the acceptance dilemma: accepting the current offer may be suboptimal, as better offers may still be presented. On the other hand, accepting too late may prevent an agreement from being reached, resulting in a break off with no gain for either party. Motivated by the challenges of bilateral negotiations between automated agents and by the results and insights of the automated negotiating agents competition (ANAC), we classify and compare state-of-the-art generic acceptance conditions. We focus on decoupled acceptance conditions, i.e. conditions that do not depend on the bidding strategy that is used. We performed extensive experiments to compare the performance of acceptance conditions in combination with a broad range of bidding strategies and negotiation domains. Furthermore we propose new acceptance conditions and we demonstrate that they outperform the other conditions that we study. In particular, it is shown that they outperform the standard acceptance condition of comparing the current offer with the offer the agent is ready to send out. We also provide insight in to why some conditions work better than others and investigate correlations between the properties of the negotiation environment and the efficacy of acceptance condition

Infrared spectroscopic studies of novel hydroxybisphosphonates and molecular modelling of their interaction with hydroxyapatite

Bisphosphonates (BPs) are a class of drugs widely used in the treatment of several metabolic bone disorders associated with increased bone resorption, including osteoporosis, Paget’s disease and metastic bone disease [1]. Although BPs can directly inhibit the cellular activity of osteoclasts, their ability to adsorb to bone mineral is also an important factor in determining their potency and duration of action [2]. In this study, we performed a molecular modelling analysis, by molecular mechanics, of the molecular structures of hydroxy(1H-indazol-3-yl)methylenediphosphonic acid (BP1; Figure 1a) and hydroxy(1-methyl-1H-indazol-3-yl)methylenediphosphonic acid (BP2; Figure 1b) and examined their interactions with hydroxyapatite (HA) by energy-minimising 50 different orientations for judiciously selected low energy conformers of each ligand at 10 Å from the mineral surface. We also calculated the vibrational spectra for each BP with semiempirical methods and compared then with FTIR spectra obtained experimentaly. The calculated interaction energies of the studied BPs with HA suggests that BP2 interacts stronger with hydroxyapatite than BP1. These results are in agreement with in vitro and in vivo studies of the 153Sm-BPs complexes. Complex 153Sm-BP2 showed, in vitro, higher HA binding than complex 153Sm-BP1. In vivo studies showed different farmacokinetics parameters with complex 153Sm-BP2 presenting initial higher levels of bone uptake than complex 153Sm-BP1, which concentration is increasing during the 24 h period studied

Linguistic Diversity and Coexistence: Experience of Spain and Russia

The article examines the contacting languages in regional bilingual environments and their role in the preservation of national identity and national culture in multinational states Using the example of the regional languages of Spain that have received the status of co-official languages Basque Catalan Galician Aran and Valencian the linguistic situation in autonomous entities the peculiarities of bilingualism and the types of language conflicts are studied The selected parameters are used to describe the linguistic situation in the Republic of North Ossetia-Alania The article concludes about the status of the Ossetian language the dominant role of the Russian language and the unbalanced linguistic situation1 The formation of national Ossetian identity should take place in the three-dimensional space of national all- Russian and world cultur