On Colorful Bin Packing Games

We consider colorful bin packing games in which selfish players control a set of items which are to be packed into a minimum number of unit capacity bins. Each item has one of $m\geq 2$ colors and cannot be packed next to an item of the same color. All bins have the same unitary cost which is shared among the items it contains, so that players are interested in selecting a bin of minimum shared cost. We adopt two standard cost sharing functions: the egalitarian cost function which equally shares the cost of a bin among the items it contains, and the proportional cost function which shares the cost of a bin among the items it contains proportionally to their sizes. Although, under both cost functions, colorful bin packing games do not converge in general to a (pure) Nash equilibrium, we show that Nash equilibria are guaranteed to exist and we design an algorithm for computing a Nash equilibrium whose running time is polynomial under the egalitarian cost function and pseudo-polynomial for a constant number of colors under the proportional one. We also provide a complete characterization of the efficiency of Nash equilibria under both cost functions for general games, by showing that the prices of anarchy and stability are unbounded when $m\geq 3$ while they are equal to 3 for black and white games, where $m=2$. We finally focus on games with uniform sizes (i.e., all items have the same size) for which the two cost functions coincide. We show again a tight characterization of the efficiency of Nash equilibria and design an algorithm which returns Nash equilibria with best achievable performance

Packing, Scheduling and Covering Problems in a Game-Theoretic Perspective

Many packing, scheduling and covering problems that were previously considered by computer science literature in the context of various transportation and production problems, appear also suitable for describing and modeling various fundamental aspects in networks optimization such as routing, resource allocation, congestion control, etc. Various combinatorial problems were already studied from the game theoretic standpoint, and we attempt to complement to this body of research. Specifically, we consider the bin packing problem both in the classic and parametric versions, the job scheduling problem and the machine covering problem in various machine models. We suggest new interpretations of such problems in the context of modern networks and study these problems from a game theoretic perspective by modeling them as games, and then concerning various game theoretic concepts in these games by combining tools from game theory and the traditional combinatorial optimization. In the framework of this research we introduce and study models that were not considered before, and also improve upon previously known results.Comment: PhD thesi

Assessing the allocation of aid : developmental concerns and the self-interest of donors.

In this paper, we perform a Tobit analysis of aid allocations, covering the period 1999-2002 and accounting for both altruistic and selfish donor motives. We first compare the allocative behavior of all bilateral donors taken together with that of multilateral aid agencies, and then look at nine major bilateral donors individually. It turns out that poorer countries get clearly more aid from both bilateral and multilateral donors, with the possible exception of France and Japan. Most bilateral donors and the multilateral agencies are also found to direct significantly more aid to well governed recipients if governance is measured by the World Bank?s CPIA. If the CPIA is replaced by the Kaufmann index, however, the policy orientation of aid becomes extremely weak. In contrast to a recent paper by Dollar and Levin (2004), our estimates do neither suggest that multilateral aid is more poverty and policy oriented than bilateral aid, nor that IDA performs particularly well within the group of multilateral donors. Post-conflict resolution, the third altruistic motive considered in the paper, emerges as a significant determinant of aid allocations in 2002. The importance of selfish aid motives clearly differs between bilateral and multilateral donors. We find no evidence that donor countries were able to push through their individual trade and political interests at the multilateral level. By contrast, the export-related self interest of DAC countries provided a fairly strong incentive to grant bilateral aid, as did colonial ties.Entwicklungshilfe; Geberländer; Motivation; Internationale Wirtschaftsbeziehungen; Schätzung; Welt; Entwicklungsländer;Foreign Aid Allocations , Donor Motives , Tobit Analysis;

Differential electrophysiological response during rest, self-referential, and non-self-referential tasks in human posteromedial cortex

The electrophysiological basis for higher brain activity during rest and internally directed cognition within the human default mode network (DMN) remains largely unknown. Here we use intracranial recordings in the human posteromedial cortex (PMC), a core node within the DMN, during conditions of cued rest, autobiographical judgments, and arithmetic processing. We found a heterogeneous profile of PMC responses in functional, spatial, and temporal domains. Although the majority of PMC sites showed increased broad gamma band activity (30-180 Hz) during rest, some PMC sites, proximal to the retrosplenial cortex, responded selectively to autobiographical stimuli. However, no site responded to both conditions, even though they were located within the boundaries of the DMN identified with resting-state functional imaging and similarly deactivated during arithmetic processing. These findings, which provide electrophysiological evidence for heterogeneity within the core of the DMN, will have important implications for neuroimaging studies of the DMN

Verbs and gender: the hidden agenda of a multicultural society

This study explores the issue of gender inequality displayed in action verbs found in English language secondary school textbooks using the Hidden Curriculum Theory. The two aspects of hidden curriculum are the frequency imbalance, i.e., male occurrences are more than female, and gender stereotyping based on roles, i.e., masculine against feminine activities. This study used both quantitative and qualitative methods for collecting data. Wordsmith Tools 4.0 (WST) was used to analyse five categories of action verbs: activity verbs, process verbs, verbs of bodily sensation, transitional event verbs, and momentary verbs. The concordance tool from the WST was used to tabulate occurrences based on gender portrayals. School teachers who taught English at secondary schools were also interviewed to validate the findings and link them to the theoretical framework used. The findings reveal gender inequality is evident in these textbooks