1,720,979 research outputs found
On Optimal Agendas for Multi-Issue Negotiation
No full textThis paper analyzes bilateral multi-issue negotiation where the issues are divisible, there are time constraints in the form of deadlines and discount factors, and the agents have different preferences over the issues. The issues are negotiated using the package deal procedure. The set of issues to be negotiated is a choice variable in that the agents can decide what issues to negotiate. This set is called the negotiation agenda. Since the outcome of negotiation depends on the agenda, it is important to determine what agenda maximizes an agent’s utility and is therefore its optimal agenda. To this end, this paper presents polynomial time methods for finding an agent’s optimal agenda
A linear approximation method for the Shapley value
No full textThe Shapley value is a key solution concept for coalitional games in general and voting games in particular. Its main advantage is that it provides a unique and fair solution, but its main drawback is the complexity of computing it (e.g for voting games this complexity is #P-complete). However, given the importance of the Shapley value and voting games, a number of approximation methods have been developed to overcome this complexity. Among these, Owen’s multi-linear extension method is the most time efficient, being linear in the number of players. Now, in addition to speed, the other key criterion for an approximation algorithm is its approximation error. On this dimension, the multi-linear extension method is less impressive. Against this background, this paper presents a new approximation algorithm, based on randomization, for computing the Shapley value of voting games. This method has time complexity linear in the number of players, but has an approximation error that is, on average, lower than Owen’s. In addition to this comparative study, we empirically evaluate the error for our method and show how the different parameters of the voting game affect it. Specifically, we show the following effects. First, as the number of players in a voting game increases, the average percentage error decreases. Second, as the quota increases, the average percentage error decreases. Third, the error is different for players with different weights; players with weight closer to the mean weight have a lower error than those with weight further away. We then extend our approximation to the more general k-majority voting games and show that, for n players, the method has time complexity O(k2n) and the upper bound on its approximation error is O(k2/?n)
Maximizing Revenue in Sequential Auctions
No full textWe study sequential auctions for private value objects and unit-demand bidders using second-price sealed-bid rules. We analyze this scenario from the seller's perspective and consider several approaches to increasing the total revenue. We derive the equilibrium bidding strategies for each individual auction. We then study the problem of selecting an optimal agenda, i.e., a revenue-maximizing ordering of the auctions. We describe an efficient algorithm that finds an optimal agenda in the important special case when the revenue of each auction is guaranteed to be strictly positive. We also show that the seller can increase his revenue by canceling one or more auctions, even if the number of bidders exceeds the number of objects for sale, and analyze the bidders' behavior and the seller's profit for different cancellation rules
A heuristic approximation method for the Banzhaf index for voting games
Full text linkThe Banzhaf index is a well known and widely used index for measuring the power a player has in a voting game. However, the problem of computing this index is computationally hard. To overcome this problem, a number of approximation methods were developed for one majority voting games. While it may be possible to extend some of these to k-majority games (which are generalized versions of one majority games), to date, there has been no performance analysis of these methods in the context of the Banzhaf index for k-majority games. In this paper, we fill this gap, by first presenting an approximation method for the Banzhaf index for k-majority games. This is a heuristic method that uses randomization to estimate an approximate. We then show that this method is computationally feasible. Finally, we evaluate its performance by analyzing its error of approximation, and show how the error varies with k. Specifically, we show that the average percentage error increases from 15% for games with k = 1 to 30% for games with k = 5
Automated analysis of weighted voting games
No full textWeighted voting games (WVGs) are an important mechanism for modeling scenarios where a group of agents must reach agreement on some issue over which they have different preferences. However, for such games to be effective, they must be well designed. Thus, a key concern for a mechanism designer is to structure games so that they have certain desirable properties. In this context, two such properties are PROPER and STRONG. A game is PROPER if for every coalition that is winning, its complement is not. A game is STRONG if for every coalition that is losing, its complement is not. In most cases, a mechanism designer wants games that are both PROPER and STRONG. To this end, we first show that the problem of determining whether a game is PROPER or STRONG is, in general, NP-hard. Then we determine those conditions (that can be evaluated in polynomial time) under which a given WVG is PROPER and those under which it is STRONG. Finally, for the general NP-hard case, we discuss two different approaches for overcoming the complexity: a deterministic approximation scheme and a randomized approximation method
Sequential auctions for common value objects with budget constrained bidders
Full text linkThis paper analyzes sequential auctions for budget constrained bidders, for multiple heterogeneous common value objects. In most auctions, bidders not only have valuations for objects but also have budget constraints (i.e., constraints on how much they can actually spend in an auction). Given these constraints, the bidders’ problem is to determine how much to bid in each auction. To this end, this paper analyzes the strategic behavior of bidders and determines the equilibrium bidding strategies for the individual auctions that constitute a series. We do this in an incomplete information setting where the bidders are uncertain about their budget constraints, and obtain equilibrium bidding strategies for the participants in individual auctions in a series
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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