Agents
Decentralized Planning in Stochastic Environments with Submodular Rewards
Kumar, Rajiv Ranjan (Singapore Management University) | Varakantham, Pradeep (Singapore Management University) | Kumar, Akshat (Singapore Management University)
Decentralized Markov Decision Process (Dec-MDP) provides a rich framework to represent cooperative decentralized and stochastic planning problems under transition uncertainty. However, solving a Dec-MDP to generate coordinated yet decentralized policies is NEXP-Hard. Researchers have made significant progress in providing approximate approaches to improve scalability with respect to number of agents. However, there has been little or no research devoted to finding guarantees on solution quality for approximate approaches considering multiple (more than 2 agents) agents. We have a similar situation with respect to the competitive decentralized planning problem and the Stochastic Game (SG) model. To address this, we identify models in the cooperative and competitive case that rely on submodular rewards, where we show that existing approximate approaches can provide strong quality guarantees ( a priori, and for cooperative case also posteriori guarantees). We then provide solution approaches and demonstrate improved online guarantees on benchmark problems from the literature for the cooperative case.
CoCoA: A Non-Iterative Approach to a Local Search (A)DCOP Solver
Leeuwen, Cornelis Jan van (TNO) | Pawelczak, Przemyslaw (Delft University of Technology)
We propose a novel incomplete cooperative algorithm for distributed constraint optimization problems (DCOPs) denoted as Cooperative Constraint Approximation (CoCoA). The key strategy of the algorithm is to use a semi-greedy approach in which knowledge is distributed amongst neighboring agents, and assigning a value only once instead of an iterative approach. Furthermore, CoCoA uses a unique-first approach to improve the solution quality. It is designed such that it can solve DCOPs as well as Asymmetric DCOPS, with only few messages being communicated between neighboring agents. Experimentally, through evaluating graph coloring problems, randomized (A)DCOPs, and a sensor network communication problem, we show that CoCoA is able to very quickly find solutions of high quality with a smaller communication overhead than state-of-the-art DCOP solvers such as DSA, MGM-2, ACLS, MCS-MGM and Max-Sum. In our asymmetric use case problem of a sensor network, we show that CoCoA not only finds the best solution, but also finds this solution faster than any other algorithm.
Dynamic Thresholding and Pruning for Regret Minimization
Brown, Noam (Carnegie Mellon University) | Kroer, Christian (Carnegie Mellon University) | Sandholm, Tuomas (Carnegie Mellon University)
Regret minimization is widely used in determining strategies for imperfect-information games and in online learning. In large games, computing the regrets associated with a single iteration can be slow. For this reason, pruning — in which parts of the decision tree are not traversed in every iteration — has emerged as an essential method for speeding up iterations in large games. The ability to prune is a primary reason why the Counterfactual Regret Minimization (CFR) algorithm using regret matching has emerged as the most popular iterative algorithm for imperfect-information games, despite its relatively poor convergence bound. In this paper, we introduce dynamic thresholding, in which a threshold is set at every iteration such that any action in the decision tree with probability below the threshold is set to zero probability. This enables pruning for the first time in a wide range of algorithms. We prove that dynamic thresholding can be applied to Hedge while increasing its convergence bound by only a constant factor in terms of number of iterations. Experiments demonstrate a substantial improvement in performance for Hedge as well as the excessive gap technique.
The AI Rebellion: Changing the Narrative
Aha, David W. (Naval Research Laboratory) | Coman, Alexandra (National Research Council and the Naval Research Laboratory)
Sci-fi narratives permeating the collective consciousness endow AI Rebellion with ample negative connotations. However, for AI agents, as for humans, attitudes of protest, objection, and rejection have many potential benefits in support of ethics, safety, self-actualization, solidarity, and social justice, and are necessary in a wide variety of contexts. We launch a conversation on constructive AI rebellion and describe a framework meant to support discussion, implementation, and deployment of AI Rebel Agents as protagonists of positive narratives.
Progress and Challenges in Research on Cognitive Architectures
Langley, Pat (Institute for the Study of Learning and Expertise)
This includes memory stores and the representations of elements in those memories, but not their contents, Most research in AI is analytic, in that it selects some facet which change as the result of external stimuli and internal of intelligence and attempts to understand it in detail, typically processing. In this sense, a cognitive architecture is analogous in isolation from other elements. This is balanced by to a building architecture, which describes its fixed a smaller movement, synthetic in character, that aims to discover structure (e.g., floors, rooms, and doors), but not its replaceable how different aspects of intelligence interact.
Bounded Rationality of Restricted Turing Machines
Chen, Lijie (Tsinghua University) | Tang, Pingzhong (Tsinghua University) | Wang, Ruosong (Tsinghua University)
Bounded rationality aims to understand the effects of how limited rationality affects decision-making. The traditional models in game theory and multiagent system research, such as finite automata or unrestricted Turing machine, fall short of capturing how intelligent agents make decision in realistic applications. To address this problem, we model bounded rational agents as restricted Turing machines: restrictions on running time and on storage space. We study our model under the context of two-person repeated games. In the case where the running time of Turing machines is restricted, we show that computing the best response of a given strategy is much harder than the strategy itself. In the case where the storage space of the Turing machines is restricted, we show the best response of a space restricted strategy can not be implemented by machines within the same size (up to a constant factor). Finally, we study how these restrictions affect the set of Nash equilibria in infinitely repeated games.We show restricting the agent’s computational resources will give rise to new Nash equilibria.
Selfish Knapsack
Feigenbaum, Itai (Lehman College and the Graduate Center, City University of New York) | Johnson, Matthew P. (Lehman College and the Graduate Center, City University of New York)
We study a strategic variant of the knapsack problem, in We emphasize that agents can misreport the existence of which there are n agents, each owning a set of items, where items, but not their properties--their size and value; that is, each item has a value and size. A social planner must design the planner has the power to verify the size and value of a mechanism to choose which items to include in a knapsack the reported items. One example of such a scenario is the of a certain capacity, where the total size of the chosen items allocation of a scientific resource, like time on a particle cannot exceed the capacity. Each agent gets a utility equal accelerator or NSF funding. Scientists submit research proposals, to the total value of her own items included in the knapsack, each requesting a certain amount of resource, which while the designer wishes to maximize social welfare (the would provide a certain expected scientific value. This expected sum of the utilities of the agents, which amounts to the total scientific value is evaluated/confirmed by an impartial value of the items in the knapsack).
Disarmament Games
Deng, Yuan (Duke University) | Conitzer, Vincent (Duke University)
Much recent work in the AI community concerns algorithms for computing optimal mixed strategies to commit to, as well as the deployment of such algorithms in real security applications. Another possibility is to commit not to play certain actions. If only one player makes such a commitment, then this is generally less powerful than completely committing to a single mixed strategy. However, if players can alternatingly commit not to play certain actions and thereby iteratively reduce their strategy spaces, then desirable outcomes can be obtained that would not have been possible with just a single player committing to a mixed strategy. We refer to such a setting as a disarmament game. In this paper, we study disarmament for two-player normal-form games. We show that deciding whether an outcome can be obtained with disarmament is NP-complete (even for a fixed number of rounds), if only pure strategies can be removed. On the other hand, for the case where mixed strategies can be removed, we provide a folk theorem that shows that all desirable utility profiles can be obtained, and give an efficient algorithm for (approximately) obtaining them.
Crowdsourced Outcome Determination in Prediction Markets
Freeman, Rupert (Duke University) | Lahaie, Sebastien (Microsoft Research) | Pennock, David M. (Microsoft Research)
A prediction market is a useful means of aggregating information about a future event. To function, the market needs a trusted entity who will verify the true outcome in the end. Motivated by the recent introduction of decentralized prediction markets, we introduce a mechanism that allows for the outcome to be determined by the votes of a group of arbiters who may themselves hold stakes in the market. Despite the potential conflict of interest, we derive conditions under which we can incentivize arbiters to vote truthfully by using funds raised from market fees to implement a peer prediction mechanism. Finally, we investigate what parameter values could be used in a real-world implementation of our mechanism.
On Pareto Optimality in Social Distance Games
Balliu, Alkida (Gran Sasso Science Institute) | Flammini, Michele (University of L'Aquila and Gran Sasso Science Institute) | Olivetti, Dennis (Gran Sasso Science Institute)
We investigate Pareto stability in Social Distance Games, that are coalition forming games in which agents utilities are proportional to their harmonic centralities in the respective coalitions, i.e., to the average inverse distance from the other agents. Pareto optimal solutions have been already considered in the literature as outcomes arising from the strategic interaction of the agents. In particular, they are stable under the deviation of the grand coalition, as they do not permit a simultaneous deviation by all the agents making all of them weakly better off and some strictly better off. We first show that, while computing a Pareto stable solution maximizing the social welfare is NP-hard in bounded degree graphs, a 2 min{Delta,sqrt n}-approximating one can be determined in polynomial time, where n is the number of agents and Delta the maximum node degree. We then determine asymptotically tight bounds on the Price of Pareto Optimality for several classes of social graphs arising from the following combinations: unbounded and bounded node degree, undirected and directed edges, unweighted and weighted edges.