Thanasis Lianeas

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Congestion games ignore the stochastic nature of resource delays and the risk-averse attitude of the players to uncertainty. To take these aspects into account, we introduce two variants of atomic congestion games, one with stochastic players, where each player assigns load to her strategy independently with a given probability, and another with stochastic(More)
We consider a nonatomic selfish routing model with independent stochastic travel times for each edge, represented by mean and variance latency functions that depend on arc flows. This model can apply to traffic in the Internet or in a road network. Variability negatively impacts packets or drivers, by introducing jitter in transmission delays which lowers(More)
We investigate how and to which extent one can exploit riskaversion and modify the perceived cost of the players in selfish routing so that the Price of Anarchy (PoA) is improved. We introduce small random perturbations to the edge latencies so that the expected latency does not change, but the perceived cost of the players increases due to riskaversion. We(More)
Braess’s paradox states that removing a part of a network may improve the players’ latency at equilibrium. In this work, we study the approximability of the best subnetwork problem for the class of random $${\mathcal {G}}_{n,p}$$ G n , p instances proven prone to Braess’s paradox by Valiant and Roughgarden RSA ’10 (Random Struct Algorithms 37(4):495–515,(More)
In routing games, the selfish behavior of the players may lead to a degradation of the network performance at equilibrium. In more than a few cases however, the equilibrium performance can be significantly improved if we remove some edges from the network. This counterintuitive fact, widely known as Braess’s paradox, gives rise to the (selfish) network(More)
We seek to understand when heterogeneity in user preferences yields improved outcomes in terms of overall cost. That this might be hoped for is based on the common belief that diversity is advantageous in many settings. We investigate this in the context of routing. Our main result is a sharp characterization of the network settings in which diversity(More)
Selfish routing is one of the most studied problems in algorithmic game theory, with one of the principal applications being that of routing in road networks. The majority of related work, in the many variants of the problem, deals with the inefficiency of equilibria to which users are assumed to converge. Multiple mechanisms for improving the outcomes at(More)
The inefficiency of the Wardrop equilibrium of nonatomic routing games can be eliminated by placing tolls on the edges of a network so that the socially optimal flow is induced as an equilibrium flow. A solution where the minimum number of edges are tolled may be preferable over others due to its ease of implementation in real networks. In this paper we(More)
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