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We propose and study a strategic model of hiding in a network, where the network designer chooses the links and his position in the network facing the seeker who inspects and disrupts the network. We characterize optimal networks for the hider, as well as equilibrium hiding and seeking strategies on these networks. We show that optimal networks are either equivalent to cycles or variants of a core-periphery networks where every node in the periphery is connected to a single node in the core., 27 pages

Infrastructure networks -- in communication and transport -- are a key feature of an economy. The functionality of these networks depends on the connectivity and sizes of different components. However, these networks face a variety of threats ranging from natural disasters to intelligent attacks (carried out by human agents). How should networks be defended and designed to ensure connectivity?We develop a strategic model to study this question. There are two 'players,' a designer and an adversary. The designer forms links among a given set of n nodes. These links are costly. In addition, the designer may also choose to protect some nodes at a cost. The adversary then allocates his resources to attack nodes. Successful attack on a node leads to its elimination (along with all its connections). We study the sub-game perfect equilibrium of this game.Our main finding is that if defence is affordable and reliable, then the network is sparse and heterogeneous, and either centrally or fully protected. On the other hand, if defence is relatively costly compared to linking then dense and homogeneous networks arise in equilibrium.

Our previous research presents a methodology of cooperative problem solving for belief-desire-intention (BDI) systems, based on a complete formal theory called TEAMLOG. This covers both a static part, defining individual, bilateral and collective agent attitudes, and a dynamic part, describing system reconfiguration in a dynamic, unpredictable environment. In this paper, we investigate the complexity of the satisfiability problem of the static part of TEAMLOG, focusing on individual and collective attitudes up to collective intention. Our logics for teamwork are squarely multi-modal, in the sense that different operators are combined and may interfere. One might expect that such a combination is much more complex than the basic multi-agent logic with one operator, but in fact we show that it is not the case: the individual part of TEAMLOG is PSPACE-complete, just like the single modality case. The full system, modelling a subtle interplay between individual and group attitudes, turns out to be EXPTIME-complete, and remains so even when propositional dynamic logic is added to it.

We study a non-symmetric variant of General Lotto games introduced in Hart (Int J Game Theory 36:441–460, 2008). We provide a complete characterization of optimal strategies for both players in non-symmetric discrete General Lotto games, where one of the players has an advantage over the other. By this we complete the characterization given in Hart (Int J Game Theory 36:441–460, 2008), where the strategies for symmetric case were fully characterized and some of the optimal strategies for the non-symmetric case were obtained. We find a group of completely new atomic strategies, which are used as building components for the optimal strategies. Our results are applicable to discrete variants of all-pay auctions.