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Financial Network Games [article]

Panagiotis Kanellopoulos, Maria Kyropoulou, Hao Zhou
<span title="2021-07-14">2021</span> <i > arXiv </i> &nbsp; <span class="release-stage" >pre-print</span>
We study financial systems from a game-theoretic standpoint. A financial system is represented by a network, where nodes correspond to firms, and directed labeled edges correspond to debt contracts between them. The existence of cycles in the network indicates that a payment of a firm to one of its lenders might result to some incoming payment. So, if a firm cannot fully repay its debt, then the exact (partial) payments it makes to each of its creditors can affect the cash inflow back to
more &raquo; ... We naturally assume that the firms are interested in their financial well-being (utility) which is aligned with the amount of incoming payments they receive from the network. This defines a game among the firms, that can be seen as utility-maximizing agents who can strategize over their payments. We are the first to study financial network games that arise under a natural set of payment strategies called priority-proportional payments. We investigate the existence and (in)efficiency of equilibrium strategies, under different assumptions on how the firms' utility is defined, on the types of debt contracts allowed between the firms, and on the presence of other financial features that commonly arise in practice. Surprisingly, even if all firms' strategies are fixed, the existence of a unique payment profile is not guaranteed. So, we also investigate the existence and computation of valid payment profiles for fixed payment strategies.
<span class="external-identifiers"> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/2107.06623v1">arXiv:2107.06623v1</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/hfb3rjonrbgc3mkmlbhrrjoywi">fatcat:hfb3rjonrbgc3mkmlbhrrjoywi</a> </span>
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Modified Schelling Games [article]

Panagiotis Kanellopoulos, Maria Kyropoulou, Alexandros A. Voudouris
<span title="2020-05-25">2020</span> <i > arXiv </i> &nbsp; <span class="release-stage" >pre-print</span>
We introduce the class of modified Schelling games in which there are different types of agents who occupy the nodes of a location graph; agents of the same type are friends, and agents of different types are enemies. Every agent is strategic and jumps to empty nodes of the graph aiming to maximize her utility, defined as the ratio of her friends in her neighborhood over the neighborhood size including herself. This is in contrast to the related literature on Schelling games which typically
more &raquo; ... mes that an agent is excluded from her neighborhood whilst computing its size. Our model enables the utility function to capture likely cases where agents would rather be around a lot of friends instead of just a few, an aspect that was partially ignored in previous work. We provide a thorough analysis of the (in)efficiency of equilibria that arise in such modified Schelling games, by bounding the price of anarchy and price of stability for both general graphs and interesting special cases. Most of our results are tight and exploit the structure of equilibria as well as sophisticated constructions.
<span class="external-identifiers"> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/2005.12149v1">arXiv:2005.12149v1</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/jerbogduqnb5vgtgbr3ykvzlyq">fatcat:jerbogduqnb5vgtgbr3ykvzlyq</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20200822140512/https://arxiv.org/pdf/2005.12149v1.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/62/b4/62b48c58ad2fb2bb9e6824e39e01932ec3f60014.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/2005.12149v1" title="arxiv.org access"> <button class="ui compact blue labeled icon button serp-button"> <i class="file alternate outline icon"></i> arxiv.org </button> </a>

Stable Fractional Matchings [article]

Ioannis Caragiannis, Aris Filos-Ratsikas, Panagiotis Kanellopoulos, Rohit Vaish
<span title="2020-12-24">2020</span> <i > arXiv </i> &nbsp; <span class="release-stage" >pre-print</span>
We study a generalization of the classical stable matching problem that allows for cardinal preferences (as opposed to ordinal) and fractional matchings (as opposed to integral). After observing that, in this cardinal setting, stable fractional matchings can have much higher social welfare than stable integral ones, our goal is to understand the computational complexity of finding an optimal (i.e., welfare-maximizing) or nearly-optimal stable fractional matching. We present simple approximation
more &raquo; ... algorithms for this problem with weak welfare guarantees and, rather unexpectedly, we furthermore show that achieving better approximations is hard. This computational hardness persists even for approximate stability. To the best of our knowledge, these are the first computational complexity results for stable fractional matchings. En route to these results, we provide a number of structural observations.
<span class="external-identifiers"> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/1902.06698v2">arXiv:1902.06698v2</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/fodx5zag4fa6xe2bnq4sszemxy">fatcat:fodx5zag4fa6xe2bnq4sszemxy</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20201228223314/https://arxiv.org/pdf/1902.06698v2.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/19/e1/19e179e5bf332b2a306bb380707e4eaf839fbcee.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/1902.06698v2" title="arxiv.org access"> <button class="ui compact blue labeled icon button serp-button"> <i class="file alternate outline icon"></i> arxiv.org </button> </a>

On Discrete Truthful Heterogeneous Two-Facility Location [article]

Panagiotis Kanellopoulos, Alexandros A. Voudouris, Rongsen Zhang
<span title="2021-09-09">2021</span> <i > arXiv </i> &nbsp; <span class="release-stage" >pre-print</span>
We revisit the discrete heterogeneous two-facility location problem, in which there is a set of agents that occupy nodes of a line graph, and have private approval preferences over two facilities. When the facilities are located at some nodes of the line, each agent derives a cost that is equal to her total distance from the facilities she approves. The goal is to decide where to locate the two facilities, so as to (a) incentivize the agents to truthfully report their preferences, and (b)
more &raquo; ... e a good approximation of the minimum total (social) cost or the maximum cost among all agents. For both objectives, we design deterministic strategyproof mechanisms with approximation ratios that significantly outperform the state-of-the-art, and complement these results with (almost) tight lower bounds.
<span class="external-identifiers"> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/2109.04234v1">arXiv:2109.04234v1</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/xwz5peqtqjh63bhyvwzfcsiy4y">fatcat:xwz5peqtqjh63bhyvwzfcsiy4y</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20210915205233/https://arxiv.org/pdf/2109.04234v1.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/b4/d3/b4d36cfcdc8e5447307d9eeb8b17ecdc25af8c5d.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/2109.04234v1" title="arxiv.org access"> <button class="ui compact blue labeled icon button serp-button"> <i class="file alternate outline icon"></i> arxiv.org </button> </a>

Intelligent Systems and Knowledge Management (Part II)

Dimitris Kanellopoulos, Sotiris Kotsiantis, Panagiotis Pintelas, D. Kanellopoulos, S. Kotsiantis, P. Pintelas
<span title="2011-06-09">2011</span> <i title="IOS Press"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/apgojvxpevcsdgm54apqo6popu" style="color: black;">Journal of Computational Methods in Sciences and Engineering</a> </i> &nbsp;
Kanellopoulos et al. / Intelligent Systems and Knowledge Management (Part II) respect to adequately adapting to the web evolution is taken into account.  ...  The second paper, by Panagiotis Doulgeris, Stelios Hadjidimitriou, Konstantinos Panoulas, Leontios Hadjileontiadis and Stavros Panas, studies the perception of musical structure combined with mirror neuron  ... 
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.3233/jcm-2011-0366">doi:10.3233/jcm-2011-0366</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/4pendgcugzgntpqde4p3kp3gjy">fatcat:4pendgcugzgntpqde4p3kp3gjy</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20171026001330/https://content.iospress.com/download/journal-of-computational-methods-in-sciences-and-engineering/jcm00366?id=journal-of-computational-methods-in-sciences-and-engineering%2Fjcm00366" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/79/e4/79e4d199ca808116e053dc9a35ce718c5f291ebd.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.3233/jcm-2011-0366"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> Publisher / doi.org </button> </a>

How game complexity affects the playing behavior of synthetic agents [article]

Chairi Kiourt, Dimitris Kalles, Panagiotis Kanellopoulos
<span title="2018-07-07">2018</span> <i > arXiv </i> &nbsp; <span class="release-stage" >pre-print</span>
Agent based simulation of social organizations, via the investigation of agents' training and learning tactics and strategies, has been inspired by the ability of humans to learn from social environments which are rich in agents, interactions and partial or hidden information. Such richness is a source of complexity that an effective learner has to be able to navigate. This paper focuses on the investigation of the impact of the environmental complexity on the game playing-and-learning behavior
more &raquo; ... of synthetic agents. We demonstrate our approach using two independent turn-based zero-sum games as the basis of forming social events which are characterized both by competition and cooperation. The paper's key highlight is that as the complexity of a social environment changes, an effective player has to adapt its learning and playing profile to maintain a given performance profile
<span class="external-identifiers"> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/1807.02648v1">arXiv:1807.02648v1</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/ck3pu6zhjvdfbacxrkambrzc5u">fatcat:ck3pu6zhjvdfbacxrkambrzc5u</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20191019035111/https://arxiv.org/pdf/1807.02648v1.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/89/d8/89d813586262aa48af59c62ed68454eebed86d70.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/1807.02648v1" title="arxiv.org access"> <button class="ui compact blue labeled icon button serp-button"> <i class="file alternate outline icon"></i> arxiv.org </button> </a>

Scheduling to maximize participation

Ioannis Caragiannis, Christos Kaklamanis, Panagiotis Kanellopoulos, Evi Papaioannou
<span title="">2008</span> <i title="Elsevier BV"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/elaf5sq7lfdxfdejhkqbtz6qoq" style="color: black;">Theoretical Computer Science</a> </i> &nbsp;
Scheduling Nash equilibria Approximation and online algorithms Competitive analysis a b s t r a c t We study a problem of scheduling client requests to servers. Each client has a particular latency requirement at each server and may choose either to be assigned to some server in order to get serviced provided that her latency requirement is met, or not to participate in the assignment at all. From a global perspective, in order to optimize the performance of such a system, one would aim to
more &raquo; ... ize the number of clients that participate in the assignment. However, clients may behave selfishly in the sense that, each of them simply aims to participate in an assignment and get serviced by some server where her latency requirement is met with no regard to overall system performance. We model this selfish behavior as a strategic game, show how to compute pure Nash equilibria efficiently, and assess the impact of selfishness on system performance. We also show that the problem of optimizing performance is computationally hard to solve, even in a coordinated way, and present efficient approximation and online algorithms.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1016/j.tcs.2008.04.031">doi:10.1016/j.tcs.2008.04.031</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/hgmqci5lhjfrjebzc66x6u544y">fatcat:hgmqci5lhjfrjebzc66x6u544y</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20190220164505/https://core.ac.uk/download/pdf/82440711.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/0b/75/0b75af66cb689abe75b1fefeab03a5e58a6478af.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1016/j.tcs.2008.04.031"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> elsevier.com </button> </a>

On Low-Envy Truthful Allocations [chapter]

Ioannis Caragiannis, Christos Kaklamanis, Panagiotis Kanellopoulos, Maria Kyropoulou
<span title="">2009</span> <i title="Springer Berlin Heidelberg"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/2w3awgokqne6te4nvlofavy5a4" style="color: black;">Lecture Notes in Computer Science</a> </i> &nbsp;
We study the problem of allocating a set of indivisible items to players having additive utility functions over the items. We consider allocations in which no player envies the bundle of items allocated to the other players too much. We present a simple proof that deterministic truthful allocations do not minimize envy by characterizing the truthful mechanisms for two players and two items. Also, we present an analysis for uniformly random allocations which are naturally truthful in
more &raquo; ... These results simplify or improve previous results of Lipton et al.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/978-3-642-04428-1_10">doi:10.1007/978-3-642-04428-1_10</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/obq6t36yyvg2pn46r2cuw3dh2q">fatcat:obq6t36yyvg2pn46r2cuw3dh2q</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20170809015301/http://students.ceid.upatras.gr/~kanellop/pubs/envy-adt09.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/fd/b0/fdb00c6c0706a8ff2d4c410a6ba959f0b691be91.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/978-3-642-04428-1_10"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> springer.com </button> </a>

The Efficiency of Fair Division [chapter]

Ioannis Caragiannis, Christos Kaklamanis, Panagiotis Kanellopoulos, Maria Kyropoulou
<span title="">2009</span> <i title="Springer Berlin Heidelberg"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/2w3awgokqne6te4nvlofavy5a4" style="color: black;">Lecture Notes in Computer Science</a> </i> &nbsp;
In this paper we study the impact of fairness on the efficiency of allocations. We consider three different notions of fairness, namely proportionality, envy-freeness, and equitability for allocations of divisible and indivisible goods and chores. We present a series of results on the price of fairness under the three different notions that quantify the efficiency loss in fair allocations compared to optimal ones. Most of our bounds are either exact or tight within constant factors. Our study
more &raquo; ... of an optimistic nature and aims to identify the potential of fairness in allocations.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/978-3-642-10841-9_45">doi:10.1007/978-3-642-10841-9_45</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/dzn3rrz5hnhwtazs6bn6hbczhm">fatcat:dzn3rrz5hnhwtazs6bn6hbczhm</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20170705092857/http://students.ceid.upatras.gr/%7Ekanellop/pubs/envy_TOCS.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/95/84/9584337ff349bcbc7cf24026a4b32c2df0e2b5c4.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/978-3-642-10841-9_45"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> springer.com </button> </a>

Taxes for Linear Atomic Congestion Games [chapter]

Ioannis Caragiannis, Christos Kaklamanis, Panagiotis Kanellopoulos
<span title="">2006</span> <i title="Springer Berlin Heidelberg"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/2w3awgokqne6te4nvlofavy5a4" style="color: black;">Lecture Notes in Computer Science</a> </i> &nbsp;
We study congestion games where players aim to access a set of resources. Each player has a set of possible strategies and each resource has a function associating the latency it incurs to the players using it. Players are non-cooperative and each wishes to follow strategies that minimize her own latency with no regard to the global optimum. Previous work has studied the impact of this selfish behavior to system performance. In this paper, we study the question of how much the performance can
more &raquo; ... improved if players are forced to pay taxes for using resources. Our objective is to extend the original game so that selfish behavior does not deteriorate performance. We consider atomic congestion games with linear latency functions and present both negative and positive results. Our negative results show that optimal system performance cannot be achieved even in very simple games. On the positive side, we show that there are ways to assign taxes that can improve the performance of linear congestion games by forcing players to follow strategies where the total latency suffered is within a factor of 2 of the minimum possible; this result is shown to be tight. Furthermore, even in cases where in the absence of taxes the system behavior may be very poor, we show that the total disutility of players (latency plus taxes) is not much larger than the optimal total latency. Besides existential results, we show how to compute taxes in time polynomial in the size of the game by solving convex quadratic programs. Similar questions have been extensively studied in the model of non-atomic congestion games. To the best of our knowledge, this is the first study of the efficiency of taxes in atomic congestion games.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/11841036_19">doi:10.1007/11841036_19</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/vs3x6uc7bbcddmcmkovbfwp5va">fatcat:vs3x6uc7bbcddmcmkovbfwp5va</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20070709232302/http://www.ceid.upatras.gr:80/caragian/esa06.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/ed/d9/edd97acc5e6900581f6473389bf90b99358dd53e.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/11841036_19"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> springer.com </button> </a>

On Interim Envy-Free Allocation Lotteries [article]

Ioannis Caragiannis, Panagiotis Kanellopoulos, Maria Kyropoulou
<span title="2021-02-26">2021</span> <i > arXiv </i> &nbsp; <span class="release-stage" >pre-print</span>
With very few exceptions, recent research in fair division has mostly focused on deterministic allocations. Deviating from this trend, we study the fairness notion of interim envy-freeness (iEF) for lotteries over allocations, which serves as a sweet spot between the too stringent notion of ex-post envy-freeness and the very weak notion of ex-ante envy-freeness. iEF is a natural generalization of envy-freeness to random allocations in the sense that a deterministic envy-free allocation is iEF
more &raquo; ... hen viewed as a degenerate lottery). It is also certainly meaningful as it allows for a richer solution space, which includes solutions that are provably better than envy-freeness according to several criteria. Our analysis relates iEF to other fairness notions as well, and reveals tradeoffs between iEF and efficiency. Even though several of our results apply to general fair division problems, we are particularly interested in instances with equal numbers of agents and items where allocations are perfect matchings of the items to the agents. Envy-freeness can be trivially decided and (when it can be achieved, it) implies full efficiency in this setting. Although computing iEF allocations in matching allocation instances is considerably more challenging, we show how to compute them in polynomial time, while also maximizing several efficiency objectives. Our algorithms use the ellipsoid method for linear programming and efficient solutions to a novel variant of the bipartite matching problem as a separation oracle. We also study the extension of interim envy-freeness notion when payments to or from the agents are allowed. We present a series of results on two optimization problems, including a generalization of the classical rent division problem to random allocations using interim envy-freeness as the solution concept.
<span class="external-identifiers"> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/2102.07839v2">arXiv:2102.07839v2</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/p2nqk5fcv5g7hpms5amefvtfqy">fatcat:p2nqk5fcv5g7hpms5amefvtfqy</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20210218222731/https://arxiv.org/pdf/2102.07839v1.pdf" title="fulltext PDF download [not primary version]" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <span style="color: #f43e3e;">&#10033;</span> <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/c6/59/c6595f8f2957126961091f8085edc1d1882cf182.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener" href="https://arxiv.org/abs/2102.07839v2" title="arxiv.org access"> <button class="ui compact blue labeled icon button serp-button"> <i class="file alternate outline icon"></i> arxiv.org </button> </a>

Revenue Guarantees in Sponsored Search Auctions [chapter]

Ioannis Caragiannis, Christos Kaklamanis, Panagiotis Kanellopoulos, Maria Kyropoulou
<span title="">2012</span> <i title="Springer Berlin Heidelberg"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/2w3awgokqne6te4nvlofavy5a4" style="color: black;">Lecture Notes in Computer Science</a> </i> &nbsp;
Sponsored search auctions are the main source of revenue for search engines. In such an auction, a set of utility-maximizing advertisers compete for a set of ad slots. The assignment of advertisers to slots depends on bids they submit; these bids may be different than the true valuations of the advertisers for the slots. Variants of the celebrated VCG auction mechanism guarantee that advertisers act truthfully and, under mild assumptions, lead to revenue or social welfare maximization. Still,
more &raquo; ... e sponsored search industry mostly uses generalized second price (GSP) auctions; these auctions are known to be non-truthful and suboptimal in terms of social welfare and revenue. In an attempt to explain this tradition, we study a Bayesian setting where the valuations of advertisers are drawn independently from a regular probability distribution. In this setting, it is well known by the work of Myerson (1981) that the optimal revenue is obtained by the VCG mechanism with a particular reserve price that depends on the probability distribution. We show that by appropriately setting the reserve price, the revenue over any Bayes-Nash equilibrium of the game induced by the GSP auction is at most a small constant fraction of the optimal revenue, improving recent results of Lucier, Paes Leme, and Tardos (2012). Our analysis is based on the Bayes-Nash equilibrium conditions and on the properties of regular probability distributions.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/978-3-642-33090-2_23">doi:10.1007/978-3-642-33090-2_23</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/llsafsxlhzawlkhlgfgocsclju">fatcat:llsafsxlhzawlkhlgfgocsclju</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20170828234059/http://students.ceid.upatras.gr/~kanellop/pubs/revenue.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/84/94/84943f896f754350739eab26e6745f445b3c560c.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/978-3-642-33090-2_23"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> springer.com </button> </a>

The Efficiency of Fair Division

Ioannis Caragiannis, Christos Kaklamanis, Panagiotis Kanellopoulos, Maria Kyropoulou
<span title="2011-09-08">2011</span> <i title="Springer Nature"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/qj6jzeossfhihfshwf7nb7lbcq" style="color: black;">Theory of Computing Systems</a> </i> &nbsp;
In this paper we study the impact of fairness on the efficiency of allocations. We consider three different notions of fairness, namely proportionality, envy-freeness, and equitability for allocations of divisible and indivisible goods and chores. We present a series of results on the price of fairness under the three different notions that quantify the efficiency loss in fair allocations compared to optimal ones. Most of our bounds are either exact or tight within constant factors. Our study
more &raquo; ... of an optimistic nature and aims to identify the potential of fairness in allocations.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/s00224-011-9359-y">doi:10.1007/s00224-011-9359-y</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/ivrdlpkof5br5bxp7azlvho4r4">fatcat:ivrdlpkof5br5bxp7azlvho4r4</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20170705092857/http://students.ceid.upatras.gr/%7Ekanellop/pubs/envy_TOCS.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/95/84/9584337ff349bcbc7cf24026a4b32c2df0e2b5c4.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1007/s00224-011-9359-y"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> springer.com </button> </a>

Taxes for linear atomic congestion games

Ioannis Caragiannis, Christos Kaklamanis, Panagiotis Kanellopoulos
<span title="2010-11-01">2010</span> <i title="Association for Computing Machinery (ACM)"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/xjsyokeq6nawdowtypazhyoyli" style="color: black;">ACM Transactions on Algorithms</a> </i> &nbsp;
We study congestion games where players aim to access a set of resources. Each player has a set of possible strategies and each resource has a function associating the latency it incurs to the players using it. Players are non-cooperative and each wishes to follow strategies that minimize her own latency with no regard to the global optimum. Previous work has studied the impact of this selfish behavior to system performance. In this paper, we study the question of how much the performance can
more &raquo; ... improved if players are forced to pay taxes for using resources. Our objective is to extend the original game so that selfish behavior does not deteriorate performance. We consider atomic congestion games with linear latency functions and present both negative and positive results. Our negative results show that optimal system performance cannot be achieved even in very simple games. On the positive side, we show that there are ways to assign taxes that can improve the performance of linear congestion games by forcing players to follow strategies where the total latency suffered is within a factor of 2 of the minimum possible; this result is shown to be tight. Furthermore, even in cases where in the absence of taxes the system behavior may be very poor, we show that the total disutility of players (latency plus taxes) is not much larger than the optimal total latency. Besides existential results, we show how to compute taxes in time polynomial in the size of the game by solving convex quadratic programs. Similar questions have been extensively studied in the model of non-atomic congestion games. To the best of our knowledge, this is the first study of the efficiency of taxes in atomic congestion games.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1145/1868237.1868251">doi:10.1145/1868237.1868251</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/zxaerp2mn5fydjskhtohagcaom">fatcat:zxaerp2mn5fydjskhtohagcaom</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20070709232302/http://www.ceid.upatras.gr:80/caragian/esa06.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/ed/d9/edd97acc5e6900581f6473389bf90b99358dd53e.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1145/1868237.1868251"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> acm.org </button> </a>

Informal music learning, improvisation and teacher education

Ruth Wright, Panagiotis Kanellopoulos
<span title="2010-01-26">2010</span> <i title="Cambridge University Press (CUP)"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/g2rtkeyx7vbf7fgu7d2mauewgy" style="color: black;">British Journal of Music Education</a> </i> &nbsp;
I n t r o d u c t i o n : I n f o r m a l l e a r n i n g a n d t h e d e v e l o p m e n t o f a c r i t i c a l p e r s p e c t i v e t o w a r d s m u s i c e d u c a t i o n At the age of four, a child I knew drew extraordinarily vibrant, imaginative trees. Crayon, chalk, colored pen, and silly putty were all useful. These trees were remarkable in how clearly they showed the bulbous lobes and branchy veins of individual leaves in a kind of cubist, all-the-way-around view that would have
more &raquo; ... ghted Picasso. Meticulous observation of real trees, and a certain daring that is characteristic of four-year-olds, combined to produce these striking artworks.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1017/s0265051709990210">doi:10.1017/s0265051709990210</a> <a target="_blank" rel="external noopener" href="https://fatcat.wiki/release/3wf233ujwjfono74blqn33du24">fatcat:3wf233ujwjfono74blqn33du24</a> </span>
<a target="_blank" rel="noopener" href="https://web.archive.org/web/20170808205433/http://hugoribeiro.com.br/biblioteca-digital/Wright_Kanellopoulos-Informal_music_learning.pdf" title="fulltext PDF download" data-goatcounter-click="serp-fulltext" data-goatcounter-title="serp-fulltext"> <button class="ui simple right pointing dropdown compact black labeled icon button serp-button"> <i class="icon ia-icon"></i> Web Archive [PDF] <div class="menu fulltext-thumbnail"> <img src="https://blobs.fatcat.wiki/thumbnail/pdf/a4/1d/a41dfdac42ee722b6ef125192842e8aab4415a30.180px.jpg" alt="fulltext thumbnail" loading="lazy"> </div> </button> </a> <a target="_blank" rel="external noopener noreferrer" href="https://doi.org/10.1017/s0265051709990210"> <button class="ui left aligned compact blue labeled icon button serp-button"> <i class="external alternate icon"></i> cambridge.org </button> </a>
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