CAPIR: Collaborative Action Planning with Intention Recognition

AAAI Conferences

We apply decision theoretic techniques to construct non-player characters that are able to assist a human player in collaborative games. The method is based on solving Markov decision processes, which can be difficult when the game state is described by many variables. To scale to more complex games, the method allows decomposition of a game task into subtasks, each of which can be modelled by a Markov decision process. Intention recognition is used to infer the subtask that the human is currently performing, allowing the helper to assist the human in performing the correct task. Experiments show that the method can be effective, giving near-human level performance in helping a human in a collaborative game.


Authorial Idioms for Target Distributions in TTD-MDPs

AAAI Conferences

In designing Markov Decision Processes (MDP), one must define the world, its dynamics, a set of actions, and a reward function. MDPs are often applied in situations where there is a clear choice of reward functions and in these cases significant care must be taken to construct a reward function that induces the desired behavior. In this paper, we consider an analogous design problem: crafting a target distribution in Targeted Trajectory Distribution MDPs (TTD-MDPs). TTD-MDPs produce probabilistic policies that minimize divergence from a target distribution of trajectories from an underlying MDP. They are an extension of MDPs that provide variety of experience during repeated execution. Here, we present a brief overview of TTD-MDPs with approaches for constructing target distributions. Then we present a novel authorial idiom for creating target distributions using prototype trajectories. We evaluate these approaches on a drama manager for an interactive game.


Applying Discrete PCA in Data Analysis

arXiv.org Machine Learning

Methods for analysis of principal components in discrete data have existed for some time under various names such as grade of membership modelling, probabilistic latent semantic analysis, and genotype inference with admixture. In this paper we explore a number of extensions to the common theory, and present some application of these methods to some common statistical tasks. We show that these methods can be interpreted as a discrete version of ICA. We develop a hierarchical version yielding components at different levels of detail, and additional techniques for Gibbs sampling. We compare the algorithms on a text prediction task using support vector machines, and to information retrieval.


How a Bayesian Approaches Games Like Chess

AAAI Conferences

Eric B. Baum 1 NEC Research Institute, 4 Independence Way, Princeton NJ 08540 eric@research.NJ.NEC.COM Abstract The point of game tree search is to insulate oneself from errors in the evaluation function. The standard approach is to grow a full width tree as deep as time allows, and then value the tree as if the leaf evaluations were exact. This has been effective in many games because of the computational efficiency of the alpha-beta algorithm. A Bayesian would suggest instead to train a model of one's uncertainty. This model adds extra information in addition to the standard evaluation function. Within such a formal model, there is an optimal tree growth procedure and an optimal method of valueing the tree. We describe how to optimally value the tree, and how to approximate on line the optimal tree to search.


A Hierarchical Approach to Generating Maps Using Markov Chains

AAAI Conferences

In this paper we describe a hierarchical method for procedurallygenerating maps using Markov chains. Ourmethod takes as input a collection of human-authoredtwo-dimensional maps, and splits them into high-leveltiles which capture large structures. Markov chains arethen learned from those maps to capture the structure ofboth the high-level tiles, as well as the low-level tiles.Then, the learned Markov chains are used to generatenew maps by first generating the high-level structure ofthe map using high-level tiles, and then generating thelow-level layout of the map. We validate our approachusing the game Super Mario Bros., by evaluating thequality of maps produced using different configurationsfor training and generation.