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The Philosophy of AI and the AI of Philosophy
The philosophy of X, where X is a science, involves philosophers analyzing the concepts of X and sometimes commenting on what concepts are or are not likely to be coherent. Artificial intelligence (AI) has closer scientific connections with philosophy than do other sciences, because AI shares many concepts with philosophy, e.g. This article treats the philosophy of AI but also analyzes some concepts common to philosophy and AI from the standpoint of AI. The philosophy of X often involves advice to practitioners of X about what they can and cannot do. We partly reverse the usual course and offer advice to philosophers, especially philosophers of mind.
Belief Tracking for Planning with Sensing: Width, Complexity and Approximations
We consider the problem of belief tracking in a planning setting where states are valuations over a set of variables that are partially observable, and beliefs stand for the sets of states that are possible. While the problem is intractable in the worst case, it has been recently shown that in deterministic conformant and contingent problems, belief tracking is exponential in a width parameter that is often bounded and small. In this work, we extend these results in two ways. First, we introduce a width notion that applies to non-deterministic problems as well, develop a factored belief tracking algorithm that is exponential in the problem width, and show how it applies to existing benchmarks. Second, we introduce a meaningful, powerful, and sound approximation scheme, beam tracking, that is exponential in a smaller parameter, the problem causal width, and has much broader applicability. We illustrate the value of this algorithm over large instances of problems such as Battleship, Minesweeper, and Wumpus, where it yields state-of-the-art performance in real-time.
Demand Side Energy Management via Multiagent Coordination in Consumer Cooperatives
Veit, A., Xu, Y., Zheng, R., Chakraborty, N., Sycara, K.
A key challenge in creating a sustainable and energy-efficient society is to make consumer demand adaptive to the supply of energy, especially to the renewable supply. In this article, we propose a partially-centralized organization of consumers (or agents), namely, a consumer cooperative that purchases electricity from the market. In the cooperative, a central coordinator buys the electricity for the whole group. The technical challenge is that consumers make their own demand decisions, based on their private demand constraints and preferences, which they do not share with the coordinator or other agents. We propose a novel multiagent coordination algorithm, to shape the energy demand of the cooperative. To coordinate individual consumers under incomplete information, the coordinator determines virtual price signals that it sends to the consumers to induce them to shift their demands when required. We prove that this algorithm converges to the central optimal solution and minimizes the electric energy cost of the cooperative. Additionally, we present results on the time complexity of the iterative algorithm and its implications for agents' incentive compatibility. Furthermore, we perform simulations based on real world consumption data to (a) characterize the convergence properties of our algorithm and (b) understand the effect of differing demand characteristics of participants as well as of different price functions on the cost reduction. The results show that the convergence time scales linearly with the agent population size and length of the optimization horizon. Finally, we observe that as participants' flexibility of shifting their demands increases, cost reduction increases and that the cost reduction is not sensitive to variation in consumption patterns of the consumers.
A Plug&Play P300 BCI Using Information Geometry
Barachant, Alexandre, Congedo, Marco
Abstract--This paper presents a new classification methods for Event Related Potentials (ERP) based on an Information geometry framework. Through a new estimation of covariance matrices, this work extend the use of Riemannian geometry, which was previously limited to SMR-based BCI, to the problem of classification of ERPs. As compared to the state-of-the-art, this new method increases performance, reduces the number of data needed for the calibration and features good generalisation across sessions and subjects. This method is illustrated on data recorded with the P300-based game brain invaders. Finally, an online and adaptive implementation is described, where the BCI is initialized with generic parameters derived from a database and continiously adapt to the individual, allowing the user to play the game without any calibration while keeping a high accuracy. So far we have conceived a Brain-Computer Interface (BCI) as a learning machine where the classifier is trained in a calibration phase preceding immediately the actual BCI use [1]. Depending on the BCI paradigm and on the efficiency of the classifier, the calibration phase may last from a few to several minutes. Regardless the duration, the very necessity of a calibration session reduces drastically the usability and appealing of a BCI. This is true both for clinically-oriented BCI, where the cognitive skills of patients are often limited and are wasted in the calibration phase, and for healthy users where the plug&play operation is nowadays considered as a minimum requirement for any consumer interfaces and devices. Besides the essential considerations from the user perspective, it appears evident that training the BCI at the beginning of each session and discarding the calibration data at the end is a very inefficient way to proceed. The problem we pose here is: can we design a "plug&play" BCI? Of course, such a goal does not imply that the BCI is not calibrated.
Arbitration and Stability in Cooperative Games with Overlapping Coalitions
Zick, Y., Markakis, E., Elkind, E.
Overlapping Coalition Formation (OCF) games, introduced by Chalkiadakis, Elkind, Markakis, Polukarov and Jennings in 2010, are cooperative games where players can simultaneously participate in several coalitions. Capturing the notion of stability in OCF games is a difficult task:deviating players may continue to contribute resources to joint projects with non-deviators, and the crucial question is what payoffs the deviators expect to receive from such projects. Chalkiadakis et al. introduce three stability concepts for OCF games---the conservative core, the refined core, and the optimistic core---that are based on different answers to this question. In this paper, we propose a unified framework for the study of stability in the OCF setting, which encompasses the stability concepts considered by Chalkiadakis et al. as well as a wide variety of alternative stability concepts. Our approach is based on the notion of arbitration functions, which determine the payoff obtained by the deviators, given their deviation and the current allocation of resources. We provide a characterization of stable outcomes under arbitration. We then conduct an in-depth study of four types of arbitration functions, which correspond to four notions of the core; these include the three notions of the core considered by Chalkiadakis et al. Our results complement those of Chalkiadakis et al. and answer questions left open by their work. In particular, we show that OCF games with the conservative arbitration function are essentially equivalent to non-OCF games, by relating the conservative core of an OCF game to the core of a non-overlapping cooperative game, and use this result to obtain a strictly weaker sufficient condition for conservative core non-emptiness than the one given by Chalkiadakis et al.
A sequential reduction method for inference in generalized linear mixed models
Generalized linear mixed models are a natural and widely used class of models, but one in which the likelihood often involves an integral of very high dimension. Because of this intractability, many alternative methods have been developed for inference in these models. One class of approaches involves replacing the likelihood with some approximation, for example using Laplace's method or importance sampling. However, these approximations can fail in cases where the structure of the model is sparse, in that only a small amount of information is available on each random effect, especially when the data are binary. If there are n random effects in total, the likelihood may always be written as an n-dimensional integral over these random effects. If there are a large number of random effects, then it will be computationally infeasible to obtain an accurate approximation to this n-dimensional integral by direct numerical integration.
A study of the fixed points and spurious solutions of the FastICA algorithm
The FastICA algorithm is one of the most popular iterative algorithms in the domain of linear independent component analysis. Despite its success, it is observed that FastICA occasionally yields outcomes that do not correspond to any true solutions (known as demixing vectors) of the ICA problem. These outcomes are commonly referred to as spurious solutions. Although FastICA is among the most extensively studied ICA algorithms, the occurrence of spurious solutions are not yet completely understood by the community. In this contribution, we aim at addressing this issue. In the first part of this work, we are interested in the relationship between demixing vectors, local optimizers of the contrast function and (attractive or unattractive) fixed points of FastICA algorithm. Characterizations of these sets are given, and an inclusion relationship is discovered. In the second part, we investigate the possible scenarios where spurious solutions occur. We show that when certain bimodal Gaussian mixtures distributions are involved, there may exist spurious solutions that are attractive fixed points of FastICA. In this case, popular nonlinearities such as "gauss" or "tanh" tend to yield spurious solutions, whereas only "kurtosis" may give reliable results. Some advices are given for the practical choice of nonlinearity function.
Nonparametric ridge estimation
Genovese, Christopher R., Perone-Pacifico, Marco, Verdinelli, Isabella, Wasserman, Larry
We study the problem of estimating the ridges of a density function. Ridge estimation is an extension of mode finding and is useful for understanding the structure of a density. It can also be used to find hidden structure in point cloud data. We show that, under mild regularity conditions, the ridges of the kernel density estimator consistently estimate the ridges of the true density. When the data are noisy measurements of a manifold, we show that the ridges are close and topologically similar to the hidden manifold. To find the estimated ridges in practice, we adapt the modified mean-shift algorithm proposed by Ozertem and Erdogmus [J. Mach. Learn. Res. 12 (2011) 1249-1286]. Some numerical experiments verify that the algorithm is accurate.
Sensing Subjective Well-being from Social Media
Hao, Bibo, Li, Lin, Gao, Rui, Li, Ang, Zhu, Tingshao
Subjective Well-being(SWB), which refers to how people experience the quality of their lives, is of great use to public policy-makers as well as economic, sociological research, etc. Traditionally, the measurement of SWB relies on time-consuming and costly self-report questionnaires. Nowadays, people are motivated to share their experiences and feelings on social media, so we propose to sense SWB from the vast user generated data on social media. By utilizing 1785 users' social media data with SWB labels, we train machine learning models that are able to "sense" individual SWB from users' social media. Our model, which attains the state-by-art prediction accuracy, can then be used to identify SWB of large population of social media users in time with very low cost.