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A Bayesian Model for Plan Recognition in RTS Games Applied to StarCraft
Synnaeve, Gabriel (University of Grenoble, LPPA at Collège de France, E-Motion at INRIA Rhône-Alpes) | Bessière, Pierre (Collège de France, CNRS UMR 7152)
The task of keyhole (unobtrusive) plan recognition is central to adaptive game AI. “Tech trees” or “build trees” are the core of real-time strategy (RTS) game strategic (long term) planning. This paper presents a generic and simple Bayesian model for RTS build tree prediction from noisy observations, which parameters are learned from replays (game logs). This unsupervised machine learning approach involves minimal work for the game developers as it leverage players’ data (com- mon in RTS). We applied it to StarCraft1 and showed that it yields high quality and robust predictions, that can feed an adaptive AI.
AIPaint: A Sketch-Based Behavior Tree Authoring Tool
Becroft, David (Worcester Polytechnic Institute) | Bassett, Jesse (Worcester Polytechnic Institute) | Mejia, Adrian (Worcester Polytechnic Institute) | Rich, Charles (Worcester Polytechnic Institute) | Sidner, Candace (Research Professor, Computer Science Department)
Current behavior authoring tools force game designers to split their attention between the game context and the tool context. We have addressed this problem by developing a behavior authoring tool that merges these two contexts. This paper outlines the design and implementation of a gameindependent behavior tree authoring tool, called AIPaint, that allows a designer to create and edit behavior trees via a natural sketching interface overlaid on the game world. We demonstrate the use of AIPaint to author computercontrolled characters in two simple games and report on an observational evaluation.
Build Order Optimization in StarCraft
Churchill, David (University of Alberta) | Buro, Michael (University of Alberta)
In recent years, real-time strategy (RTS) games have gained interest in the AI research community for their multitude of challenging subproblems — such as collaborative pathfinding, effective resource allocation and unit targeting, to name a few. In this paper we consider the build order problem in RTS games in which we need to find concurrent action sequences that, constrained by unit dependencies and resource availability, create a certain number of units and structures in the shortest possible time span. We present abstractions and heuristics that speed up the search for approximative solutions considerably in the game of StarCraft, and show the efficacy of our method by comparing its real-time performance with that of professional StarCraft players.
Computational Caricatures: Probing the Game Design Process with AI
Smith, Adam M. (University of California, Santa Cruz) | Mateas, Michael (University of California, Santa Cruz)
We propose the creation of computational caricatures as a design research practice that aims to advance understanding of the game design process and to develop the reusable technology for design automation. Computational caricatures capture and exaggerate statements about the game design process in the form of computational systems (i.e. software and hardware). In comparison with empirical interviews of game designers, arguments from established design theory, and the creation of neutral simulations of the design process, computational caricatures provide more direct access to inquiry and insight about design. Further, they tangibly demonstrate architectures and subsystems for a new generation of human-assisting design support systems and adaptive games that embed aspects of automated design in their runtime processes. In this paper, we frame the idea of computational caricature, review several existing design automation prototypes through the lens of caricature, and call for more design research to be done following this practice.
The Case for Intention Revision in Stories and its Incorporation into IRIS, a Story-Based Planning System
Fendt, Matthew William (North Carolina State University) | Young, R. Michael (North Carolina State University)
Character intention revision is an essential component of stories, but it has yet to be incorporated into story generation systems. However, intentionality, one component of intention revision, has been explored in both narrative generation and logical formalisms. The IRIS system adopts the belief/desire/intention framework of intentionality from logical formalisms and combines it with preexisting concepts of intentionality in narrative. IRIS also introduces the crucial concept of intention revision for characters in the story. The intent of this synthesis is to create stories with dynamic and believable characters that update their beliefs, replan, and revise their intentions over the course of the story.
Learning Policies for First Person Shooter Games Using Inverse Reinforcement Learning
Tastan, Bulent (University of Central Florida) | Sukthankar, Gita Reese (University of Central Florida)
The creation of effective autonomous agents (bots) for combat scenarios has long been a goal of the gaming industry. However, a secondary consideration is whether the autonomous bots behave like human players; this is especially important for simulation/training applications which aim to instruct participants in real-world tasks. Bots often compensate for a lack of combat acumen with advantages such as accurate targeting, predefined navigational networks, and perfect world knowledge, which makes them challenging but often predictable opponents. In this paper, we examine the problem of teaching a bot to play like a human in first-person shooter game combat scenarios. Our bot learns attack, exploration and targeting policies from data collected from expert human player demonstrations in Unreal Tournament. We hypothesize that one key difference between human players and autonomous bots lies in the relative valuation of game states. To capture the internal model used by expert human players to evaluate the benefits of different actions, we use inverse reinforcement learning to learn rewards for different game states. We report the results of a human subjects' study evaluating the performance of bot policies learned from human demonstration against a set of standard bot policies. Our study reveals that human players found our bots to be significantly more human-like than the standard bots during play. Our technique represents a promising stepping-stone toward addressing challenges such as the Bot Turing Test (the CIG Bot 2K Competition).
Corpus Annotation in Service of Intelligent Narrative Technologies
Finlayson, Mark Alan (Massachusetts Institute of Technology)
Annotated corpora have stimulated great advances in the language sciences. The time is ripe to bring that same stimulation, and consequent benefits, to computational approaches to narrative. I describe an effort to construct a corpus of semantically annotated stories. I outline the structure of the corpus, a structure which colloquially can be described as a "handful of handfuls." One handful of the corpus has already been constructed, viz., 18k words of Russian folktales. There are two handfuls under construction: legal cases focused on the area of probable cause, and stories from Islamist Extremist Jihadists. Four more handfuls are being planned: folktales from Chinese, English, and a West Asian culture, and stories of international conventional and cyber conflicts. There are numerous additional handfuls under discussion. The main focus of the corpus so far has been on textual materials that are annotated for their surface semantics using conventional annotation tools and techniques; nonetheless, there are numerous novel dimensions along which the corpus might grow and become useful for different communities. In particular I propose for discussion the outlines of a few novel sources, annotation schemes, and collection methodologies that could potentially make the corpus of great use to the interactive narrative or narrative generation communities.
The Story Workbench: An Extensible Semi-Automatic Text Annotation Tool
Finlayson, Mark Alan (Massachusetts Institute of Technology)
Text annotations are of great use to researchers in the language sciences, and much effort has been invested in creating annotated corpora for an wide variety of purposes. Unfortunately, software support for these corpora tends to be quite limited: it is usually ad-hoc, poorly designed and documented, or not released for public use. I describe an annotation tool, the Story Workbench, which provides a generic platform for text annotation. It is free, open-source, cross-platform, and user friendly. It provides a number of common text annotation operations, including representations (e.g., tokens, sentences, parts of speech), functions (e.g., generation of initial annotations by algorithm, checking annotation validity by rule, fully manual manipulation of annotations) and tools (e.g., distributing texts to annotators via version control, merging doubly-annotated texts into a single file). The tool is extensible at many different levels, admitting new representations, algorithm, and tools. I enumerate ten important features and illustrate how they support the annotation process at three levels: (1) annotation of individual texts by a single annotator, (2) double-annotation of texts by two annotators and an adjudicator, and (3) annotation scheme development. The Story Workbench is scheduled for public release in March 2012.
Initial Results for Measuring Four Dimensions of Narrative Conflict
Ware, Stephen G. (North Carolina State University) | Harrison, Brent (North Carolina State University) | Young, R. Michael (North Carolina State University) | Roberts, David L. (North Carolina State University)
Conflict is an essential element of interesting stories. In previous work, we proposed a formal model of narrative conflict. We also described 7 dimensions which can be used to distinguish one conflict from another: participants, subject, duration, balance, directness, intensity, and resolution. This paper presents the results of an experiment designed to measure how well our metrics for balance, directness, intensity, and resolution predict the responses of human readers when asked to measure these same values in a set of four stories. We conclude that our metrics are able to rank stories similarly to human readers.
An Object-Oriented Approach to Reinforcement Learning in an Action Game
Mohan, Shiwali (University of Michigan, Ann Arbor) | Laird, John E. (University of Michigan )
In this work, we look at the challenge of learning in an action game,Infinite Mario. Learning to play an action game can be divided intotwo distinct but related problems, learning an object-relatedbehavior and selecting a primitive action. We propose a framework that allows for the use of reinforcement learning for both ofthese problems. We present promising results in some instances of thegame and identify some problems that might affect learning.