Showing papers presented at "Conference on Computability in Europe in 2009"

Evaluation of a pervasive game for domestic energy engagement among teenagers

Abstract: In this article, we present Power Agent—a pervasive game designed to encourage teenagers and their families to reduce energy consumption in the home. The ideas behind this mobile phone-based game are twofold; to transform the home environment and its devices into a learning arena for hands-on experience with electricity usage and to promote engagement via a team competition scheme. We report on the game's evaluation with six teenagers and their families who played the game for ten days in two cities in Sweden. Data collection consisted of home energy measurements before, during, and after a game trial, in addition to interviews with participants at the end of the evaluation. The results suggest that the game concept was highly efficient in motivating and engaging the players and their families to change their daily energy-consumption patterns during the game trial. Although the evaluation does not permit any conclusions as to whether the game had any postgame effects on behavior, we can conclude that the pervasive persuasive game approach appears to be highly promising in regard to energy conservation and similar fields or issues.

What went wrong? A survey of problems in game development

Abstract: Despite its growth and profitability, many reports about game projects show that their production is not a simple task, but one beset by common problems and still distant from having a healthy and synergetic work process The goal of this article is to survey the problems in the development process of electronic games, which are mainly collected from game postmortems, by exploring their similarities and differences to well-known problems in traditional information systems

Designing universally accessible games

Abstract: Today, computer games are one of the major sources of entertainment Computer games are usually far more demanding than typical interactive applications in terms of motor and sensory skills needed for interaction control, due to special-purpose input devices, complicated interaction techniques, and the primary emphasis on visual control and attention This renders computer games inaccessible to a large percentage of people with disabilities This article introduces the concept of universally accessible games, that is, games proactively designed to optimally fit and adapt to individual gamer characteristics and to be concurrently played among people with diverse abilities, without requiring particular adjustments or modifications The concept is elaborated and tested through four case studies: a web-based chess game (UA-Chess), an action game (Access Invaders), a universally inaccessible game (Game Overe) used as an interactive educational tool, and an improved version of Access Invaders (Terrestrial Invaders) For all cases, key design and evaluation findings are discussed, reporting consolidated know-how and experience Finally, the research challenge of creating multiplayer universally accessible games is further elaborated, proposing the novel concept of Parallel Game Universes as a potential solution

Graph States and the Necessity of Euler Decomposition

Abstract: Coecke and Duncan recently introduced a categorical formalisation of the interaction of complementary quantum observables. In this paper we use their diagrammatic language to study graph states, a computationally interesting class of quantum states. We give a graphical proof of the fixpoint property of graph states. We then introduce a new equation, for the Euler decomposition of the Hadamard gate, and demonstrate that Van den Nest's theorem--locally equivalent graphs represent the same entanglement--is equivalent to this new axiom. Finally we prove that the Euler decomposition equation is not derivable from the existing axioms.

Enhancing the educational value of video games

Abstract: Lowering the barrier between education and real entertainment is an important challenge in order to better exploit the potential of computers and reach a demographic that is traditionally averse to learning. To this end, it is important to investigate how to exploit the appeal of video games (VGs) to also favor and induce learning via playing video games. Achieving this goal is not only a matter of content, since simply “superimposed” educational content risks being perceived as boring. Hence we believe that the game should feature mechanisms for acquiring knowledge and skill that are smoothly embedded in a meaningful, homogeneous, and compelling whole. Thus, there is a need to compartmentalize components of a game engine so that it becomes easy and efficient to integrate the graphics/interface—which has already been done very well by state-of-the-art successful video games and the educational aspect which is typically poor in those same games. Hence we have defined a general set of mechanisms and modules that can be inserted in state-of-the-art VG environments and are aimed at promoting various kinds of knowledge and procedural skill acquisition. In order to investigate and validate this concept, we have built an educational game, SeaGame, using a state-of-the-art commercial game development approach, and enriched the environment with instances of developed educational modules. Analyzing user test results, we conclude that SeaGame is perceived quite similarly to commercial VGs, which suggests that the proposed mechanisms do not compromise the overall enjoyability of the game, which is key to attracting a wide demographic that is not currently involved in educational activities during their leisure time. The results of this research can be generalized, since the standards of commercial games and the proposed educational enhancements can be instantiated in a variety of educational contexts and applied to different types of content.

Player motivations: A psychological perspective

Abstract: Although player motivation is one of the main concerns of computer gaming, research so far has been able to identify only a limited set of motives, which are not founded on formal theories of human motivation. Assuming that goal-directed behavior is triggered by the interaction between personal and environmental factors, this article aims to analyze a broader range of gaming motivations derived from basic human needs. The psychological needs investigated in this study are based on the psychogenic needs divided into six categories: materialism, power, affiliation, achievement, information, and sensual needs, defined by Murray [1938] in his extensive research. Since the present work defines motivation as a product of continuous interactions between players and the virtual world, each individual psychological need is briefly described in terms of the actions it provokes. In this context, this article is not concerned with why people play computer games but how they are motivated in the game. Detailed analysis of the conceptual components of player motivation focuses on matching each psychological need to common gaming situations in computer role-playing games (RPGs). Since this game genre provides interactive virtual environments capable of offering experiences analogous to real life, it is highly relevant to motivational studies. The relationship between motivational factors and gaming situations is discussed with examples from a recently released RPG, which takes place in a fantasy world full of social issues and conflicts, where players usually find themselves in situations that require a choice between the lesser of two evils. It is expected that the variables defined in this study should facilitate the design of computer games that satisfy a broader range of player motivations by providing ways to investigate the relationship between psychological needs and the gaming environment, while bearing in mind the basic components of goal-directed behavior.

An Application of Martin-Löf Randomness to Effective Probability Theory

Abstract: In this paper we provide a framework for computable analysis of measure, probability and integration theories. We work on computable metric spaces with computable Borel probability measures. We introduce and study the framework of layerwise computability which lies on Martin-Lof randomness and the existence of a universal randomness test. We then prove characterizations of effective notions of measurability and integrability in terms of layerwise computability. On the one hand it gives a simple way of handling effective measure theory, on the other hand it provides powerful tools to study Martin-Lof randomness, as illustrated in a sequel paper.

Survey on Oblivious Routing Strategies

Abstract: We give a survey about recent advances in the design of oblivious routing algorithms. These routing algorithms choose their routing paths independent of the traffic in the network and they are therefore very well suited for distributed environments in which no central entitiy exist that could make routing decisions based on the whole traffic pattern in the network.

Ordinal Computability

Abstract: Ordinal computability uses ordinals instead of natural numbers in abstract machines like register or Turing machines. We give an overview of the computational strengths of *** -β -machines, where *** and β bound the time axis and the space axis of some machine model. The spectrum ranges from classical Turing computability to ***-***-computability which corresponds to Godel 's model of constructible sets. To illustrate some typical techniques we prove a new result on Infinite Time Register Machines (= ***-*** -register machines) which were introduced in [6]: a real number x *** *** 2 is computable by an Infinite Time Register Machine iff it is Turing computable from some finitely iterated hyperjump 0(n ).

Notes on the Jump of a Structure

Abstract: We introduce the notions of a complete set of computably infinitary $\Pi^0_n$ relations on a structure, of the jump of a structure , and of admitting n th jump inversion .

Automatic prototyping in model-driven game development

Abstract: Model-driven game development (MDGD) is an emerging paradigm where models become first-order elements in game development, maintenance, and evolution. In this article, we present a first approach to 2D platform game prototyping automatization through the use of model-driven engineering (MDE). Platform-independent models (PIM) define the structure and the behavior of the games and a platform-specific model (PSM) describes the game control mapping. Automatic MOFscript transformations from these models generate the software prototype code in C++. As an example, Bubble Bobble has been prototyped in a few hours following the MDGD approach. The resulting code generation represents 93p of the game prototype.

Interactive documentaries: A Golden Age

Abstract: This article is motivated by the opportunity presented by recent advances in information and communication technology—particularly by faster broadband connections and faster digital media processing capabilities—for interactive television to extend and develop interactive storytelling or interactive narratives. This will give viewers the ability to shape and configure the programs they watch, while watching, according to their needs and desires. Rather than consuming a predefined linear narration—represented by the traditional dramatic or factual program—which has to address the potential audience as a whole, individuals or groups of viewers can receive tailored-made personal narratives. Each viewer can thus potentially become an active explorer of a narrative space rather than a receiver of a predefined narration. This article presents the production of A Golden Age, an interactive configurable documentary about the arts of the Renaissance in England, as a comprehensive illustration of the potential offered by interactive narration. At the same time, it is also a successful example of the employment of the recently developed, production- and genre-independent, ShapeShifting Media technology in the realization of a good quality interactive narrative. This article describes the concept of A Golden Age, the content production process, carried out from the outset with the aim of producing an interactive experience, and, finally, its authoring and delivery with the ShapeShifting Media toolkit. The focus of the presentation is on the design and implementation of the computational interactive narrative structures expressed in the Narrative Structure Language (NSL), the declarative representation language underlying ShapeShifting Media. A Golden Age places a distinct emphasis on the quality and style of each emerging individual narration, aiming at levels at least comparable to those of (good quality) linearly compiled documentaries. NSL and the ShapeShifting Media toolkit provided the means to achieve this. A Golden Age is a production realized by Illuminations Television Ltd, London, in collaboration with Goldsmiths, University of London and BT over a period of more or less two years. Approximately 50 hours of rushes were filmed for its production. A Golden Age has already inspired the production of another similar documentary, Films of Fact, soon to be released in the public domain as an installation at the Science Museum, London, and, it is hoped, will continue to serve as inspiration for other interactive documentaries.

Video interviews

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An adaptative game loop architecture with automatic distribution of tasks between CPU and GPU

Abstract: This article presents a new architecture to implement all game loop models for games and real-time applications that use the GPU as a mathematics and physics coprocessor, working in parallel processing mode with the CPU. The presented model applies automatic task distribution concepts. The architecture can apply a set of heuristics defined in Lua scripts in order to get acquainted with the best processor for handling a given task. The model applies the GPGPU (general-purpose computation on GPUs) paradigm. In this article we propose an architecture that acquires knowledge about the hardware by running tasks in each processor and, by studying their performance over time, finding the best processor for a group of tasks.

Lower Bounds for Kernelizations and Other Preprocessing Procedures

Abstract: We first present a method to rule out the existence of strong polynomial kernelizations of parameterized problems under the hypothesis P $ e$ NP. This method is applicable, for example, to the problem Sat parameterized by the number of variables of the input formula. Then we obtain improvements of related results in [1,6] by refining the central lemma of their proof method, a lemma due to Fortnow and Santhanam. In particular, assuming that PH $ e \Sigma^{\rm {P}}_3$, i.e., that the polynomial hierarchy does not collapse to its third level, we show that every parameterized problem with a "linear OR" and with NP-hard underlying classical problem does not have polynomial reductions to itself that assign to every instance x with parameter k an instance y with |y | = k O (1)·|x |1 *** *** (here *** is any given real number greater than zero).

Boids that see: Using self-occlusion for simulating large groups on GPUs

Abstract: Behavioral models have been used in the entertainment industry to increase the realism in the simulation of large groups of individuals. Unfortunately, the classical models can be very compute-intensive when very large groups are considered, reducing its applicability in games and other interactive systems. In this article we explore both search space reduction and parallelism to improve the performance of Reynold's Boids model. We propose a methodology that considers self-occlusion (visibility culling) to reduce the number of neighbors and we take advantage the parallelism present in common graphics processor units (GPUs) to allow the simulation of very large groups. We performed different GPU implementations (GPGPU and CUDA); the results show that visibility culling allows significant gains in performance without affecting the model's overall behavior.

Physical interfaces for tabletop games

Abstract: IncreTable is a mixed-reality tabletop game inspired by The Incredible Machine. Users can combine real and virtual game pieces in order to solve puzzles in the game. Game actions include placing virtual domino blocks with digital pens, controlling a virtual car by modifying the virtual terrain through a depth camera interface, and controlling real robots to topple over real and virtual dominoes.

Meet the new boss

Abstract: “We feel that we have recreated the mass media.” So said Kim Malone Scott, director of sales and operations for Google’s AdSense, to the New York Times about the Seth MacFarlane deal in an apparent effort to announce the arrival of the new boss. Is Google the new boss? No, despite assertions to the contrary the great majority of the money and the eyeballs remain with the traditional mass media networks, and this will continue to be so. Is Google’s online syndication business model the new boss, one that can and will be adapted by other media networks? We all agree that the old dinosaur of a business model is dying a quick death, and so we consider which new species is evolving to take its place in the media ecosystem. What does this new species look like? How does it function? In general, it is smaller and more nimble, its DNA mutates much more quickly than that of the old dinosaurs, and so it is more capable of continually adapting to changing environments. One example of this new business model is the deal between Google and MacFarlane, one facilitated by Media Rights Capital, the ad agency Crispin Porter + Bogusky and their client Burger King. As I write this article in October 2008, this deal has accumulated 14 million views in its first three weeks. A network television show that averaged 5 million viewers a week wouldn’t be an “American Idol” or “Grey’s Anatomy”, so while these are impressive numbers for online video, it is not the number of eyeballs to date that is of greatest interest but rather the underlying business model that generates them, on both the advertising and content sides. So how does it work, what is this new business model that Google and Seth MacFarlane are using? In short, it’s pull instead of push. The content is not pushed toward viewers from one central location, but rather they are encouraged to pull on it from many decentralized locations. MacFarlane’s videos are distributed across thousands of websites using Google’s AdSense, instead of being anchored to one specific destination or network. In terms of targeting, the videos aren’t sent to random websites but rather to those that are known to be frequented by MacFarlane’s primary demographic of young males; it’s online syndication across Google’s websites as well those of its numerous third-party partners. Consumer pulls can be multiplied exponentially, since each video clip can be quickly and easily shared via recommendation to one’s friends and/or by embedding the video into one’s webpage or blog. Who is funding this new business model, how are these videos monetized? As with a traditional television network, the videos are funded by advertising, in this case from Burger King. Every time someone clicks on one of MacFarlane’s videos, BK pays a fee that is divided up among the creator, MRC, Google, and the website hosting that copy of the video. The more viewers cotton to a particular video, the more they share it with their friends, the more funds roll in courtesy

The gamer experience: Investigating relationships between culture and usability in massively multiplayer online games

Abstract: Massively multiplayer online games (MMOGs) are persisted virtual worlds capable of supporting hundreds or thousands of gamers simultaneously. Although every MMOG environment has its own “culture,” gamers originate from different countries, speak different languages, and have different national cultural backgrounds. It is assumed that gamers' cultural diversity affects their online gaming experience and their perceptions of a game's usability; nevertheless knowledge is limited and relevant research is rare. This study aims for an empirical investigation between gamers' cultural dimensions and their perceptions of usability. A subjective measurement of usability is given in this study; usability is viewed in more holistic terms, beyond its functional dimensions, so as to capture social and affective dimensions as well, which are very important within the MMOG context. The findings of this exploratory study indicate that there are quantitative relationships between culture and the perception of usability of MMOGs. Such results have practical implications for the designers of MMOGs. A relevant discussion is also presented, along with future research dimensions.

Equivalence Relations on Classes of Computable Structures

Abstract: If $\mathcal{L}$ is a finite relational language then all computable $\mathcal{L}$-structures can be effectively enumerated in a sequence in such a way that for every computable $\mathcal{L}$-structure $\mathcal{B}$ an index n of its isomorphic copy can be found effectively and uniformly. Having such a universal computable numbering, we can identify computable structures with their indices in this numbering. If K is a class of $\mathcal{L}$-structures closed under isomorphism we denote by K c the set of all computable members of K . We measure the complexity of a description of K c or of an equivalence relation on K c via the complexity of the corresponding sets of indices. If the index set of K c is hyperarithmetical then (the index sets of) such natural equivalence relations as the isomorphism or bi-embeddability relation are $\Sigma^1_1$. In the present paper we study the status of these $\Sigma^1_1$ equivalence relations (on classes of computable structures with hyperarithmetical index set) within the class of $\Sigma^1_1$ equivalence relations as a whole, using a natural notion of hyperarithmetic reducibility.

Elaborating eight elements of fun: Supporting design of pervasive player enjoyment

Abstract: This article presents the validation of the Pervasive GameFlow model (PGF), a model for analyzing player enjoyment in pervasive gaming. The model can be used as both a heuristic guideline for designers and as evaluation criteria in user-centered evaluation of pervasive games, but also as a framework for understanding player experiences in pervasive gaming on a more general level. The theoretical background and perspective on game design and the design- support approach that the PGF model represents are explained, and the concept of the magic circle is discussed. The eight elements of the PGF model (concentration, challenge, player skills, control, clear goals, feedback, immersion, and social interaction) were validated by evaluating a crossmedia game prototype (a subgenre of pervasive games) called Furiae. The comparative importance of the eight elements of the PGF model and their effects on the pervasive gaming experience was a focus of the evaluation, in which questionnaires (qualitative) and focus group interviews were used to capture how the players graded the importance of the eight elements in playing Furiae. The study revealed that seven of the eight elements seem to be of specific importance, as they scored relatively high in the validation. The top three elements according to the results are concentration (games should require concentration and the player should be able to concentrate on the game); challenge (games should be sufficiently challenging and match the player's skill level); and immersion (players should experience deep but effortless involvement in the game). Finally, implications for design are discussed in terms of how some of the most important elements present challenges and possibilities for crossmedia game development.

A bidimensional data structure and spatial optimization for supermassive crowd simulation on GPU

Abstract: Computing and presenting emergent crowd simulations in real time is a computationally intensive task. This intensity is mostly due to the complexity of the traversal algorithm needed for the interactions of all elements against each other on the basis of a proximity query. By using special data structures such as grids, and due to the parallel nature of graphics hardware, relevant previou work reduced this complexity considerably, making it possible to achieve interactive frame rates. However, existing proposals tend to be heavily bound by the maximum density of such grids, which is usually high, leading to arguably inefficient algorithms. In this article we propose the use of a fine- grained grid and accompanying data manipulation, to lead to scalable algorithmic complexity. We also implement a representative flocking boids case study, from which we ran benchmarks with more than one million simulated and rendered boids at nearly 30fps. We remark that related previous work achieved no more than 15,000 boids with interactive frame rates.

An extensible framework for interactive facial animation with facial expressions, lip synchronization and eye behavior

Abstract: In this article we describe our approach to generating convincing and empathetic facial animation. Our goal is to develop a robust facial animation platform that is usable and can be easily extended. We also want to facilitate the integration of research in the area and to directly incorporate the characters in interactive applications such as embodied conversational agents and games. We have developed a framework capable of easily animating MPEG-4 parameterized faces through high-level description of facial actions and behaviors. The animations can be generated in real time for interactive applications. We present some case studies that integrate computer vision techniques in order to provide interaction between the user and a character that interacts with different facial actions according to events in the application.

Robot Arena: An augmented reality platform for game development

Abstract: Nowadays electronic games are of great importance to the economic sector, to computing, and to academic research, and not are limited to entertainment applications only. Augmented reality is one of the new frontiers to be explored in the search for innovation in gameplay and in interactive interfaces of electronic games. This article presents the research, development, and testing of an infrastructure, called Robot Arena, for the development of innovative games using the spatial augmented reality and new interfaces that this technology brings. Based on horizontal interfaces with elements of hardware and software, Robot ARena has a flexible architecture that enables different ways of interaction and visualization. Another aspect planned for this project is the control and communication of robots, which can be used as avatars in games. A Robot ARena prototype was implemented, tested, and used in the development of two game prototypes, FootBot ARena and TanSpace, which bring new challenges to the infrastructure, such as exploration of the influence of virtual objects on real objects and the application of tangible interfaces.

Members of Random Closed Sets

Abstract: The members of Martin-Lof random closed sets under a distribution studied by Barmpalias et al. are exactly the infinite paths through Martin-Lof random Galton-Watson trees with survival parameter $\frac{2}{3}$. To be such a member, a sufficient condition is to have effective Hausdorff dimension strictly greater than $\gamma=\log_2 \frac{3}{2}$, and a necessary condition is to have effective Hausdorff dimension greater than or equal to *** .

A Computation of the Maximal Order Type of the Term Ordering on Finite Multisets

Abstract: We give a sharpening of a recent result of Aschenbrenner and Pong about the maximal order type of the term ordering on the finite multisets over a wpo Moreover we discuss an approach to compute maximal order types of well-partial orders which are related to tree embeddings

Can local avatars satisfy a global audience? A case study of high-fidelity 3D facial avatar animation in subject identification and emotion perception by US and international groups

Abstract: This study investigates effectiveness of a local high-fidelity 3D facial avatar for a global audience by observing how US and International student groups differed in identifying subjects and perceiving emotions while viewing nonverbal high-fidelity 3D facial avatar animations embedded with the motion data of three US individuals. To synthesize the animated 3D avatars to convey highly believable facial expressions, a 3D scanned facial model was mapped with high-fidelity motion-capture data of three native US subjects as they spoke designated English sentences with specified emotions. Simple animations in conjunction with actual footage of the subjects speaking during the facial motion-capture sessions were shown several times to both native US and international students in similar settings. After a familiarization process, we showed the students randomly arranged talking avatars without voices and asked them to identify the corresponding identities and emotional types of the subjects whose facial expressions were utilized in the creation of the avatars, and to rate their confidence in their selections. We found that the US group had higher success rates in subject identification, although the related difference in confidence ratings between two groups was not significant. The differences in the success rates and confidence ratings on the perception of emotion between the two groups were not significant either. The results of our study provide interesting insights into avatar-based interaction where the national and/or cultural background of a person impacts the perception of identity while having little effect on the perception of emotion. However, we observed that dynamics (e.g., head motion) could offset the disadvantage of cultural unfamiliarity in subject identification. We observed that both groups performed at a nearly identical level in subject identification and emotion perception when they were shown the avatar animation with heightened expression and dynamic intensities. In addition, we observed that the confidence ratings were correlated to accuracy in identifying the subject but not to accuracy in perceiving emotion.

Event relations in plan-based plot composition

Abstract: The process of plot composition in the context of interactive storytelling is considered from a fourfold perspective, that is, from the syntagmatic, paradigmatic, antithetic, and meronymic relations between the constituent events. These relations are shown to be associated with the four major tropes of semiotic research. A conceptual model and set of facilities for interactive plot composition and adaptation dealing with the four relations is described. To accommodate antithetic relations, corresponding to the irony trope, our plan-based approach leaves room for the unplanned. A simple storyboarding prototype tool has been implemented to conduct experiments.

Stability under Strategy Switching

Abstract: We suggest that a process-like notion of strategy is relevant in the context of interactions in systems of self-interested agents. In this view, strategies are not plans formulated by rational agents considering all possible futures and (mutually recursively) taking into account strategies employed by other players. Instead, they are partial; players start with a set of potential strategies and dynamically switch between them. This necessitates some means in the model for players to access each others' strategies, and we suggest a syntax by which players' rationale for such switching may be specified and structurally composed. In such a model one can ask a stability question: given a game arena and a strategy specification, whether players eventually settle down to strategies without further switching. We show that this problem can be algorithmically solved using automata theoretic methods.

Smart composition of game objects using dependency injection

Abstract: Most game engines are based on inheritance of game objects and/or componentization of behaviors. While this approach enables clear visualization of the system architecture, good code reuse, and fast prototyping, it brings some issues, mostly related to the high dependency between game objects/components instances. This dependency often leads to static casts and null pointer references that are difficult to debug. In this article we propose the use of the dependency injection design pattern to safely initialize game objects and lessen the programmer's role in handling these issues both during the prototyping and production phases. Since these dependencies are attributes of game objects and the injection occurs only at the initialization pass, there is no performance penalty at the game loop.