An Algebraic Graphical Model for Decision with Uncertainties, Feasibilities, and Utilities

Journal of Artificial Intelligence Research

Numerous formalisms and dedicated algorithms have been designed in the last decades to model and solve decision making problems. Some formalisms, such as constraint networks, can express "simple" decision problems, while others are designed to take into account uncertainties, unfeasible decisions, and utilities. Even in a single formalism, several variants are often proposed to model different types of uncertainty (probability, possibility...) or utility (additive or not). In this article, we introduce an algebraic graphical model that encompasses a large number of such formalisms: (1) we first adapt previous structures from Friedman, Chu and Halpern for representing uncertainty, utility, and expected utility in order to deal with generic forms of sequential decision making; (2) on these structures, we then introduce composite graphical models that express information via variables linked by "local" functions, thanks to conditional independence; (3) on these graphical models, we finally define a simple class of queries which can represent various scenarios in terms of observabilities and controllabilities. A natural decision-tree semantics for such queries is completed by an equivalent operational semantics, which induces generic algorithms. The proposed framework, called the Plausibility-Feasibility-Utility (PFU) framework, not only provides a better understanding of the links between existing formalisms, but it also covers yet unpublished frameworks (such as possibilistic influence diagrams) and unifies formalisms such as quantified boolean formulas and influence diagrams. Our backtrack and variable elimination generic algorithms are a first step towards unified algorithms.

Machine learning prowess on display


More than 80 Amazon scientists and engineers will attend this year's International Conference on Machine Learning (ICML) in Stockholm, Sweden, with 11 papers co-authored by Amazonians being presented. "ICML is one of the leading outlets for machine learning research," says Neil Lawrence, director of machine learning for Amazon's Supply Chain Optimization Technologies program. "It's a great opportunity to find out what other researchers have been up to and share some of our own learnings." At ICML, members of Lawrence's team will present a paper titled "Structured Variationally Auto-encoded Optimization," which describes a machine-learning approach to optimization, or choosing the values for variables in some process that maximize a particular outcome. The first author on the paper is Xiaoyu Lu, a graduate student at the University of Oxford who worked on the project as an intern at Amazon last summer, then returned in January to do some follow-up work.

Who is Watching You Eat?

AAAI Conferences

Many of the seminal papers in preference handling have used food preferences as motivating examples for their work. As foodies, the authors find this particularly motivating. While we think that there is both research and commercial potential in preference-based software for restaurants, we believe that serious application of the MPREF community's technology to the problem of personal preference-driven presentation of menus, seating, etc., will require significant further innovation. We broadly survey the current use of preferences in making the dining-out experience more enjoyable, and we look at the states of the art for preference representation and reasoning, and for restaurant software. We illustrate some of our points with a short story.

GAI Networks for Utility Elicitation

AAAI Conferences

Assuming the decision maker behaves according to the EU model, we investigate the elicitation of generalized additively decomposable utility functions on a product set (GAI-decomposable utilities). We propose a general elicitation procedure based on a new graphical model called a GAI-network. The latter is used to represent and manage independences between attributes, as junction graphs model independences between random variables in Bayesian networks. It is used to design an elicitation questionnaire based on simple lotteries involving completely specified outcomes. Our elicitation procedure is convenient for any GAI-decomposable utility function, thus enhancing the possibilities offered by UCP-networks.

Yelling at Amazon's Alexa

The New Yorker

The first time I met Alexa, the A.I. robot voice inside the wine-bottle-size speaker known as the Amazon Echo, I was at my friends' house, in rural New England. "Currently, it is seventy-five degrees," she told us, and assured us that it would not rain. This was a year ago, and I'd never encountered a talking speaker before. When I razzed my friend for his love of gadgetry, he showed me some of Alexa's other tricks: telling us the weather, keeping a shopping list, ordering products from Amazon. This summer, Alexa decided again and again who the tickle monster's next victim was, saying their children's adorable nicknames in her strange A.I. accent.