Showing papers presented at "Conference on Computability in Europe in 2018"

Natural Walking in Virtual Reality: A Review

Abstract: Recent technological developments have finally brought virtual reality (VR) out of the laboratory and into the hands of developers and consumers. However, a number of challenges remain. Virtual travel is one of the most common and universal tasks performed inside virtual environments, yet enabling users to navigate virtual environments is not a trivial challenge—especially if the user is walking. In this article, we initially provide an overview of the numerous virtual travel techniques that have been proposed prior to the commercialization of VR. Then we turn to the mode of travel that is the most difficult to facilitate, that is, walking. The challenge of providing users with natural walking experiences in VR can be divided into two separate, albeit related, challenges: (1) enabling unconstrained walking in virtual worlds that are larger than the tracked physical space and (2) providing users with appropriate multisensory stimuli in response to their interaction with the virtual environment. In regard to the first challenge, we present walking techniques falling into three general categories: repositioning systems, locomotion based on proxy gestures, and redirected walking. With respect to multimodal stimuli, we focus on how to provide three types of information: external sensory information (visual, auditory, and cutaneous), internal sensory information (vestibular and kinesthetic/proprioceptive), and efferent information. Finally, we discuss how the different categories of walking techniques compare and discuss the challenges still facing the research community.

Natural Walking in Virtual Reality

Abstract: Recent technological developments have finally brought virtual reality (VR) out of the laboratory and into the hands of developers and consumers. However, a number of challenges remain. Virtual tra...

A Serious Game for Anesthesia-Based Crisis Resource Management Training

Abstract: Simulation-based training has been widely adopted in medical education as a tool in the practice and development of skills within a safe, controlled, and monitored environment. However, significant cost and logistical challenges exist within traditional simulation practices. The rising popularity of gaming has seen the wide application of serious games to medical education and training. Serious gaming (and virtual simulation in general) offers a viable alternative to traditional training practices, offering students/trainees the opportunity to train until they reach a specific competency level in a safe, interactive, engaging, and cost-effective manner for effective skills transfer to the real world. Here we present a serious game for anesthesia-based crisis resource management (ACRM) training. The ACRM serious game provides trainees the opportunity to react to a simulated medical emergency within a virtual operating room while providing an interactive, and engaging training experience. Results of an experiment that was conducted to examine the usability (the ease of use of the serious game and its interface) of the serious game, and its ability to engage trainees, indicate that although improvements to the user interface can be made, it shows promise as an immersive and engaging complementary training tool.

SimCEC: A Collaborative VR-Based Simulator for Surgical Teamwork Education

Abstract: Traditionally, the evaluation of surgical procedures in virtual reality (VR) simulators has been restricted to their individual technical aspects disregarding the procedures carried out by teams. However, some decision models have been proposed to support the collaborative training evaluation process of surgical teams in collaborative virtual environments. The main objective of this article is to present a collaborative simulator based on VR, named SimCEC, as a potential solution for education, training, and evaluation in basic surgical routines for teams of undergraduate students. The simulator considers both tasks performed individually and those carried in a collaborative manner. The main contribution of this work is to improve the discussion about VR simulators requirements (design and implementation) to provide team training in relevant topics, such as users’ feedback in real time, collaborative training in networks, interdisciplinary integration of curricula, and continuous evaluation.

Validation of EGameFlow: A Self-Report Scale for Measuring User Experience in Video Game Play

Abstract: The development of a relevant model for measuring user enjoyment of video game play has received a great deal of attention in game-based and flow-based literature. EGameFlow, a self-report scale instrument created from the original game enjoyment framework proposed by Sweetser and Wyeth, provides a necessary and potentially useful tool for game enjoyment researchers. However, the scale itself is quite new. The utility of EGameFlow cannot be determined until its rigorousness has been verified. The purpose of this study was to test the validity, reliability, and applicability of EGameFlow for measuring players’ experiences in video game play. A total of 167 participants played an interactive video game and then evaluated their game playing experiences via the refined 27-item EGameFlow scale, which included the following seven dimensions: concentration, goal clarity, feedback, challenge, autonomy, immersion, and social interaction. Confirmatory factor analysis, reliability testing, and discriminant validity checks were administered. Empirical results indicated that the refined scale was both valid and reliable. Implications of these findings and direction for future research were also discussed.

A Deontic Logic Reasoning Infrastructure

Abstract: A flexible infrastructure for the automation of deontic and normative reasoning is presented. Our motivation is the development, study and provision of legal and moral reasoning competencies in future intelligent machines. Since there is no consensus on the “best” deontic logic formalisms and since the answer may be application specific, a flexible infrastructure is proposed in which candidate logic formalisms can be varied, assessed and compared in experimental ethics application studies. Our work thus links the historically rich research areas of classical higher-order logic, deontic logics, normative reasoning and formal ethics.

Usertesting Without the User: Opportunities and Challenges of an AI-Driven Approach in Games User Research

Abstract: The use of human participants in game evaluation can be costly, time-consuming, and present challenges for constructing representative player samples. These challenges may be overcome by using computer-controlled agents in place of human users for certain stages of the usertesting process. This article explores opportunities and challenges in the use of behavioural modelling to create independent “user” agents driven by artificial intelligence (AI). We highlight the utility of imitating cognitive processes such as spatial reasoning, memory, and goal-oriented decision-making as a means to increase the viability of independent agents as a tool in usertesting. Specifically, we investigate the possible design and use of proxy AI “users” that mimic human navigational behaviour to assist in the evaluation of level designs. Ultimately, we propose that a configurable population of AI players can provide a data-rich supplement to current approaches in games user research.

Evolutionary Algorithms for a Better Gaming Experience in Rehabilitation Robotics

Abstract: This article proposes the use of two evolutionary algorithms (EAs) to the dynamic difficulty adjustment (DDA) of a serious game in the rehabilitation robotics application. DDA occurs in runtime for a better user experience with a game. This approach is used to improve the quality of the game experience and to avoid boredom or frustration for players with severe limitations imposed by pathologies such as stroke, cerebral palsy, and spinal cord injuries. The first EA solves the game adjustment problem, changing the game difficulty according to the player’s skill, and the purpose of the second EA is to adjust the coefficients of the first EA’s objective function so that it can work in a more effective way. To do so, the second EA uses results of game matches against simulated player profiles. The results shows that the presented method was able to identify a set of coefficients that allows the first EA to correctly adjust the difficulty level for all six tested player profiles.

A Journey to Computably Enumerable Structures (Tutorial Lectures)

Abstract: The tutorial focuses on computably enumerable (c.e.) structures. These structures form a class that properly extends the class of all computable structures. A computably enumerable (c.e.) structure is one that has computably enumerable equality relation E such that the atomic operations and relations of the structure are induced by c.e. operations and relations that respect E. Finitely presented universal algebras (e.g. groups, rings) are natural examples of c.e. structures. The first lecture gives an introduction to the theory, provides many examples, and proves several simple yet important results about c.e. structures. The second lecture addresses a particular problem about finitely presented expansions of universal algebras with an emphasis to semigroups and groups. The lecture is based on the interplay between important constructions, concepts, and results in computability (Post’s construction of simple sets), universal algebra (residual finiteness), and algebra (Golod-Shafarevich theorem). The third lecture is devoted to studying dependency of various properties of c.e. structures on their domains.

Polynomial-Time Presentations of Algebraic Number Fields

Abstract: Using an extension of the notion of polynomial time presentable structure we show that some natural presentations of the ordered field \({\mathbb R}_{\text{ alg }}\) of algebraic reals and of the field \({\mathbb C}_{\text{ alg }}\) of algebraic complex numbers are polynomial-time equivalent to each other and are polynomial time. We also establish upper complexity bounds for the problem of rational polynomial evaluation in \({\mathbb C}_{\text{ alg }}\) and for the problem of root-finding for polynomials in \({\mathbb C}_{\text{ alg }}[x]\) which improve the previously known bound.

Aspects of Independent Game Production: An Exploratory Study

Abstract: Recent years have witnessed independent game production rise to a prominent position in the digital game industry. Be it by the fresh, innovative take it brought to the scene or by its rebellious attitude towards what is perceived as mainstream, the term “indie game” has become somewhat of a buzzword. The following study displays a series of findings of research fieldwork aiming to advance the study of indie game development by investigating organizational and managerial practices commonly adopted by these developers. Relying on semi-structured interviews conducted with lead developers of seven Brazilian indie game firms, the connections, similarities, and differences among these developers’ firm structure and project management practices and those of the larger game industry is explored, utilizing the lenses of scope, organization, time, cost, and quality management as a starting point. Given the growing and significant relevance of the game industry as a whole, this empirical study offers pragmatic data on the still-niche research topic of indie games.

Functionals of Type 3 as Realisers of Classical Theorems in Analysis

Abstract: We investigate the relative computational strength of combinations of four higher order functionals, the jump and hyperjump seen as functionals of type 2 and realisers for the compactness of Cantor space and the Lindelof property of Baire space seen as functionals of type 3. We compare them with the closure operator for non-monotone inductive definitions of sets of integers, also seen as a functional of type 3.

A Taxonomy of Deviant Encodings

Abstract: The main objective of this paper is to design a common background for various philosophical discussions about adequate conceptual analysis of “computation”.

Universality in Freezing Cellular Automata

Abstract: Cellular Automata have been used since their introduction as a discrete tool of modelization. In many of the physical processes one may modelize thus (such as bootstrap percolation, forest fire or epidemic propagation models, life without death, etc), each local change is irreversible. The class of freezing Cellular Automata (FCA) captures this feature. In a freezing cellular automaton the states are ordered and the cells can only decrease their state according to this “freezing-order”.

Taming Koepke's Zoo

Abstract: For ordinals \(\alpha \) and \(\beta \), Koepke defined \((\alpha ,\beta )\)-Turing machines as Turing machines with tape length \(\alpha \) and working time bounded above by \(\beta \). So far, their computational strength was determined for \(\alpha =\beta \) exponentially closed, \(\alpha =\beta =\text {On}\) and \((\alpha ,\beta )=(\omega ,\text {On})\). In this paper, we determine the set of \((\alpha ,\beta )\)-writable subsets of \(\alpha \) when \(\alpha \) is multiplicatively closed and \(\beta >\alpha \) is admissible. This answers some open questions by Koepke in [5].

The Caixa de Pandora Game: Changing Behaviors and Attitudes toward Violence against Women

Abstract: This article presents the development issues and evaluation results of a serious game called Caixa de Pandora (Pandora's Box, in English), developed to train health professionals to care for women in situations of domestic violence. The combat of violence against women in the health sector presupposes a change of attitudes with respect to identified cases, with the exclusion of discriminatory and oppressive practices on the part of care professionals. To change these behaviors and verify postures, Caixa de Pandora uses an approach focused on the affective domain of learning. In the same sense of verifying and guiding changes in behavior, the intelligence module of the game used a model based on psychometric principles in its design. The validation of the game by a statistical sample with health professionals identified changes in their conceptions about the subject after playing the game, thereby demonstrating its pedagogical potential to formulate new knowledge and to change behavior.

Designing and Evaluating Games for Mindfulness

Abstract: This research investigates the relationship between mindfulness and digital games, by identifying which aspects of mindfulness can be trained by digital games and which game elements influence factors of mindfulness. Games and interactive approaches with research evidence for their efficacy are presented for each individual mindfulness factor, as defined by the CHIME eight-factor model of mindfulness. Two experiments were conducted to validate whether games can improve mindfulness. First, an expert review was conducted, where domain experts rated the fit of games to their associated mindfulness factor. Second, a laboratory study tested the effect of games on mindfulness, revealing positive significant effects on state mindfulness. Elaborating on the research findings from all studies, a framework is proposed to inform the design of digital games for improving mindfulness, and implications plus limitations are discussed.

Computing with SAT Oracles: Past, Present and Future

Abstract: Boolean Satisfiability (SAT) epitomizes NP-completeness, and so what is arguably the best known class of intractable problems. NP-complete decision problems are pervasive in all areas of computing, with literally thousands of well-known examples. Nevertheless, SAT solvers routinely challenge the problem’s intractability by solving propositional formulas with millions of variables, many representing the translation from some other NP-complete or NP-hard problem. The practical effectiveness of SAT solvers has motivated their use as oracles for NP, enabling new algorithms that solve an ever-increasing range of hard computational problems. This paper provides a brief overview of this ongoing effort, summarizing some of the recent past and present main successes, and highlighting directions for future research.

The Isometry Degree of a Computable Copy of $$\ell ^p$$

Abstract: Suppose p is a computable real so that \(p \ge 1\). We define the isometry degree of a computable presentation of \(\ell ^p\) to be the least powerful Turing degree \(\mathbf {d}\) by which it is \(\mathbf {d}\)-computably isometrically isomorphic to the standard presentation of \(\ell ^p\). We show that this degree always exists and that when \(p e 2\) these degrees are precisely the c.e. degrees.

Makeup Creativity Enhancement with an Augmented Reality Face Makeup System

Abstract: This study presents a novel interactive face makeup system that aims to support users to improve makeup creativity. In this system, facial feature points were tracked by Kinect and mapped to the 3D face model. The makeup tools were developed for providing a tangible interaction. A face painting application was developed based on the Unity 3D framework. While users apply makeup, the program will generate color on the model, which synchronizes with the user's movement. The results will be mapped to the user's face in real time by using a projection mapping technique that allows users to see which color is suitable for their skin tone. Users can perceive a realistic makeup feeling from our touch detectable makeup tools. Moreover, by using a computer-based drawing system, users can undo, save, and load their makeup image and compare with other styles. A subjective evaluation was conducted to evaluate the users’ satisfaction. The results indicated that by using this system, users can find a suitable makeup style for themselves and get help increasing their makeup creativity.

Parameterized Complexity and Approximation Issues for the Colorful Components Problems

Abstract: The quest for colorful components (connected components where each color is associated with at most one vertex) inside a vertex-colored graph has been widely considered in the last ten years Here we consider two variants, Minimum Colorful Components (MCC) and Maximum Edges in transitive Closure (MEC), introduced in the context of orthology gene identification in bioinformatics The input of both MCC and MEC is a vertex-colored graph MCC asks for the removal of a subset of edges, so that the resulting graph is partitioned in the minimum number of colorful connected components; MEC asks for the removal of a subset of edges, so that the resulting graph is partitioned in colorful connected components and the number of edges in the transitive closure of such a graph is maximized We study the parameterized and approximation complexity of MCC and MEC, for general and restricted instances

Elementary Bi-embeddability Spectra of Structures

Abstract: We study elementary bi-embeddability spectra, the collection of Turing degrees of elementary bi-embeddable structures. We give examples of such spectra and compare them with related notions.

Bit Complexity of Computing Solutions for Symmetric Hyperbolic Systems of PDEs (Extended Abstract).

Abstract: We establish upper bounds of bit complexity of computing solution operators for symmetric hyperbolic systems of PDEs. Here we continue the research started in our papers of 2009 and 2017, where computability, in the rigorous sense of computable analysis, has been established for solution operators of Cauchy and dissipative boundary-value problems for such systems.

Algorithms and Geometric Constructions

Abstract: It is well known that several classical geometry problems (e.g., angle trisection) are unsolvable by compass and straightedge constructions. But what kind of object is proven to be non-existing by usual arguments? These arguments refer to an intuitive idea of a geometric construction as a special kind of an “algorithm” using restricted means (straightedge and/or compass). However, the formalization is not obvious, and different descriptions existing in the literature are far from being complete and clear. We discuss the history of this notion and a possible definition in terms of a simple game.

Divide and Conquer Computation of the Multi-string BWT and LCP Array

Abstract: Indexing huge collections of strings, such as those produced by the widespread sequencing technologies, heavily relies on multi-string generalizations of the Burrows-Wheeler Transform (BWT) and the Longest Common Prefix (LCP) array, since solving efficiently both problems are essential ingredients of several algorithms on a collection of strings.

Fast and Realistic Reflections Using Screen Space and GPU Ray Tracing—A Case Study on Rigid and Deformable Body Simulations

Abstract: The realistic representation of light within a computational domain is not a trivial task. Although several rendering approaches exist, the ray tracing technique is highly regarded as robust and realistic; however, its computational cost is still prohibitive for real-time games and other 3D applications. A modern tradeoff is to pair the ray tracing with the rasterization step, the former being responsible for generating complex lighting interactions, such as reflections, while the latter is used to generate less demanding visual effects, such as diffuse lighting and shadows. The stated framework has been studied by several authors, but it has not been shown to work both efficiently and accurately for highly dynamic scenes with deformable geometry. Stepping in this direction, this work presents a case study whose goal is to generate fast and realistic reflections on rigid and deformable body simulations using a hybrid approach that brings together the Screen Space technique with the GPU ray tracing algorithm and their respective main capabilities. The results show that not only realistic reflections can be generated at interactive rates, but also that the hybrid approach allows to achieve a certain level of scalability with respect to the number of triangles updated on every frame during the simulations.

Optimized Program Extraction for Induction and Coinduction

Abstract: We prove soundness of an optimized realizability interpretation for a logic supporting strictly positive induction and coinduction. The optimization concerns the special treatment of Harrop formulas which yields simpler extracted programs. We show that wellfounded induction is an instance of strictly positive induction and derive from this a new computationally meaningful formulation of the Archimedean property for real numbers. We give an example of program extraction in computable analysis and show that Archimedean induction can be used to eliminate countable choice.

Have We Met Before? Using Consumer-Grade Brain-Computer Interfaces to Detect Unaware Facial Recognition

Abstract: Much research has been done on the brain’s reaction to seeing faces, but while much of the work has investigated the brain’s conscious reaction to faces, far less work has been done exploring the brain’s unaware reactions using consumer-grade devices. Built on previous work, we describe an experiment conducted using EEGs and consumer-grade Brain-Computer Interface (BCI) headsets to measure the brain’s unaware reaction to seeing faces of three pre-defined recognition classes: no recognition, unaware recognition, and aware recognition. We pre-select images to be shown in each class and display the images in a two-day experiment where participants implicitly learn images tagged as “unaware recognition” for use in the second day. It was found that, outperforming previous works, unaware facial recognitions could be detected with fairly high accuracies using a method that combines multiple sensors from a BCI device and utilizing out-of-the-box classification methods.

New Nonterminal Complexity Results for Semi-conditional Grammars

Abstract: A semi-conditional grammar is a form of regulated rewriting system. Each rule consists of a context-free core rule \(A\rightarrow w\) and two strings \(w_+,w_-\); the rule is applicable if \(w_+\) (the positive condition) occurs as a substring of the current sentential form, but \(w_-\) (the negative condition) does not. The maximum lengths i, j of the positive or negative conditional strings, respectively, give a natural measure of descriptional complexity, known as the degree of such grammars. Employing several normal form results on phrase-structure grammars as derived by Geffert, we improve on previously obtained results by reducing the number of nonterminals of semi-conditional grammars of a given degree (i, j) while maintaining computational completeness of the said mechanisms.

Using a Social Educational Network to Facilitate Peer-Feedback for a Virtual Simulation

Abstract: Virtual simulation offers a viable alternative to traditional educational and training practices, offering trainees the opportunity to train until they reach a specific competency level in a safe and cost-effective manner. One of the benefits of virtual simulation is the ability to provide the trainee with feedback regarding his or her performance in the simulation, thus providing the trainee the opportunity to monitor and adapt progress toward the goal. With respect to learning and development, it has been long known that feedback plays a vital role in learning; we learn faster and more effectively when we know how we are doing and what must be changed to improve our performance. Taking advantage of the benefits afforded by peer-feedback, here we present a preliminary study that examined the application of a customized social educational network—the Observational Practice and Educational Network (OPEN)—to facilitate peer-feedback with respect to recorded performances of a gamified virtual simulation session developed specifically for medical-based cultural competence training. A virtual simulation session was recorded and uploaded to OPEN, which then facilitated peer-feedback by allowing the peers and educators/experts to evaluate, provide comments, and generally discuss the recorded virtual simulation sessions. Questionnaires were employed to gauge the feasibility of a social educational network (OPEN in particular) to facilitate peer-feedback, as well as participant satisfaction with using and interacting with OPEN (i.e., examining the usability of OPEN).