Newspapers and other media often describe particular topics over some periods by giving a series ... more Newspapers and other media often describe particular topics over some periods by giving a series of texts that introduces new information and corrects previous information. By analyzing such texts, we can understand how a topic changed over time and how the media treated it. However, analyzing such texts manually is time-consuming. To solve this problem, we propose a method for visualizing texts that describe a topic changing over time. For this purpose, we first generate an event information graph from such texts by using an exiting method. Then we transform it into two different graphs. The first graph shows changes in the topic that we obtain by separating the initial graph and comparing the resulting time-dependent graphs. The second graph depicts a summary of the topic that we obtain by extracting high-frequency words from the initial graph. The results of our experiment show that our method can visualize changes and important information described in the texts.
Constraints have been playing an important role in the user interface field since its infancy. A ... more Constraints have been playing an important role in the user interface field since its infancy. A prime use of constraints in this field is to automatically maintain geometric layouts of graphical objects. To facilitate the construction of constraint-based user interface applications, researchers have proposed various constraint satisfaction methods and constraint solvers. Most previous research has focused on either local propagation or linear constraints, excluding more general nonlinear ones. However, nonlinear geometric constraints are practically useful to various user interfaces, e.g., drawing editors and information visualization systems. In this paper, we propose a novel constraint solver called Chorus, which realizes various powerful nonlinear geometric constraints such as Euclidean geometric, non-overlapping, and graph layout constraints. A key feature of Chorus is its module mechanism that allows users to define new kinds of geometric constraints. Also, Chorus supports "soft" constraints with hierarchical strengths or preferences (i.e., constraint hierarchies). We describe its framework, algorithm, implementation, and experimental results.
Event-driven programming is a paradigm that is widely used in many fields. Processing is a set of... more Event-driven programming is a paradigm that is widely used in many fields. Processing is a set of programming languages and environments specialized in event-driven programming for interactive graphical applications. It provides only low-level event-handling functions, which imposes difficulty on novice programmers in programming complex behaviors. This paper proposes a method for unit-testing event-driven Processing programs. It allows writing testable Processing programs and test programs in Java. To demonstrate how it works, this paper presents case studies on testing whether mouse and key events are correctly handled.
In the education of introductory programming, people often adopt block-based visual programming l... more In the education of introductory programming, people often adopt block-based visual programming languages such as Scratch and Blockly that allow programmers to construct programs by placing visual blocks. A previous study showed that a block-based language was more effective than a text-based language in introductory programming education. However, even with such block-based languages, it is still necessary for novices to learn programming in traditional ways, for example, by hearing lectures, reading textbooks, or watching tutorial videos. In this paper, we propose a video game-like approach to supporting novices in learning programming. We introduce two concepts into a block-based programming system: one is a staging mechanism that allows novices to gradually obtain more complex means of programming; the other is an assistant chatbot that helps novices to gain knowledge of programming. We implemented the system by applying our approach to turtle graphics. We present results of the experiment that we conducted to evaluate our approach.
ABSTRACT Real-world information can often be expressed as a graph that consists of nodes and edge... more ABSTRACT Real-world information can often be expressed as a graph that consists of nodes and edges. Graphs are often effectively represented in a visual manner. To make visual representations of graphs easily available, researchers have proposed numerous techniques for automatic visualization of graphs [1]. An important class of graphs is the general undirected graph, which imposes no restrictions on its structure as well as having no directed edges. The forcedirected approach [1] is often adopted to visualize general undirected graphs, and works well for graphs with hundreds of nodes.
Voice adaptation is an interactive speech processing technique that allows the speaker to transmi... more Voice adaptation is an interactive speech processing technique that allows the speaker to transmit with a chosen target voice. We propose a novel method that is intended for dynamic scenarios, such as online video games, where the source speaker's and target speaker's data are nonaligned. This would yield massive improvements to immersion and experience by fully becoming a character, and address privacy concerns to protect against harassment by disguising the voice. With unaligned data, traditional methods, e.g., probabilistic models become inaccurate, while recent methods such as deep neural networks (DNN) require too substantial preparation work. Common methods require multiple subjects to be trained in parallel, which constraints practicality in productive environments. Our proposal trains a subject nonparallel into a voice profile used against any unknown source speaker. Prosodic data such as pitch, power and temporal structure are encoded into RGBA-colored frames used in a multi-objective optimization problem to adjust interrelated features based on color likeness. Finally, frames are smoothed and adjusted before output. The method was evaluated using Mean Opinion Score, ABX, MUSHRA, Single Ease Questions and performance benchmarks using two voice profiles of varying sizes and lastly discussion regarding game implementation. Results show improved adaptation quality, especially in a larger voice profile, and audience is positive about using such technology in future games.
International Journal on Software Tools for Technology Transfer, Mar 19, 2011
This paper presents a bounded model checking (BMC) tool called hydlogic for hybrid systems. It tr... more This paper presents a bounded model checking (BMC) tool called hydlogic for hybrid systems. It translates a reachability problem of a nonlinear hybrid system into a predicate logic formula involving arithmetic constraints, and checks the satisfiability of the formula based on a satisfiability modulo theories (SMT) method. We tightly integrate (i) an incremental SAT solver to enumerate the possible sets of constraints and (ii) an interval-based solver for hybrid constraint systems (HCSs) to solve the constraints described in the formulas. The HCS solver verifies the occurrence of a discrete change by enclosing continuous states that may cause the discrete change by a set of boxes. We adopt the existence property of a unique solution in the boxes computed by the HCS solver as (i) a proof of the reachability of a model, and (ii) a guide in the over-approximation refinement procedure. Our hydlogic implementation successfully handled several examples including those with nonlinear constraints.
In the last decade, with the development of multi-core workstations, the availability of GPGPU-en... more In the last decade, with the development of multi-core workstations, the availability of GPGPU-enhanced systems and the access to Grid platforms and supercomputers worldwide, Parallel Programming reached mainstream programming and appeared as a key issue in order to use in an efficient manner the computing power at hand. Search methods and combinatorial optimization techniques are not isolated from this phenomenon, as bigger computing power means the ability to attack more complex combinatorial problems. In the last years some experiments have been done to extend to parallel execution search methods such as Constraint Programming or SAT solving (Boolean satisfiability), and combinatorial optimization methods such as Local Search, Meta-heuristics and Brand & Bound. However these works have mostly been done for shared memory multi-core systems (i.e. with a few cores) or for small PC clusters (a few machines). The next challenge is to devise efficient techniques and algorithms for massively parallel computers with tens or hundreds of thousands of cores in the form of heterogeneous hybrid systems based on both multi-core processors and GPUs. We would like to provide a cross-community forum for researchers working on search methods (Constraint Solving, Artificial Intelligence, Logic Programming, SAT solving, etc.), combinatorial optimization methods (metaheuristics, local search, tabu search, evolutionary algorithms, ant colony optimization, particle swarm optimization, memetic algorithms, and other types of algorithms) and High Performance Computing (Grids, large PC clusters, massively parallel computers, GPGPUs) in order to tackle the challenge of efficient implementations on all kinds of parallel hardware: multi-core, GPU-based or heterogeneous massively parallel systems. This meeting is designed to be a forum for researchers willing to tackle those issues, in order to exchange ideas, theoretical frameworks, design of algorithms and methods, implementation issues, experimental results and further boost this growing area through cross-fertilization.
Graph drawing is an information visualization technology for illustrating relations between objec... more Graph drawing is an information visualization technology for illustrating relations between objects. Interactive graph drawing is often important since it is difficult to statically lay out complex graphs. For the interactive drawing of general undirected graphs, we have proposed the high-dimensional approach, which uses static graph layouts in high-dimensional spaces to dynamically find twodimensional layouts according to user interaction. Although the resulting interactive graph drawing method was found to be fast, other properties of it are not yet clear. In this paper, we analyze the high-dimensional approach to further explore its properties. Specifically, we perform the following two kinds of its analysis: (1) sensitivity analysis for investigating how the high-dimensional approach places graph nodes on the two-dimensional plane; (2) empirical analysis for examining the appropriateness of underlying graph layout methods. The results show that, as an underlying graph layout method, Kruskal and Seery's method based on Torgerson's multidimensional scaling method is more appropriate for the high-dimensional approach than other methods for computing graph layouts in high-dimensional spaces.
In formula-based fault localization methods, a program under test, which is unrolled to a certain... more In formula-based fault localization methods, a program under test, which is unrolled to a certain bound, is encoded in a trace formula (TF). The efficiency and precision of the fault localization algorithm depend highly on the way this formula is encoded. The full flow-sensitive TF can cover all potential root causes, but is usually large and scalability problems remain. We propose a new encoding, the hardened flow-sensitive trace formula (HFTF), which reduces the complexity of the formula but does not lose essential control flow graph (CFG) information required for localizing faults. The HFTF is constructed using a concolic execution method that generates both failing and successful executions and uses the coverage information from these executions to simplify the trace formula.
The paper tackles the problems of the “giant hairballs”, the dense and tangled structures often r... more The paper tackles the problems of the “giant hairballs”, the dense and tangled structures often resulting from visualization of large social graphs. Proposed is a high-dimensional rotation technique called AGI3D, combined with an ability to filter elements based on social centrality values. AGI3D is targeted for a high-dimensional embedding of a social graph and its projection onto 3D space. It allows the user to rotate the social graph layout in the high-dimensional space by mouse dragging of a vertex. Its high-dimensional rotation effects give the user an illusion that he/she is destructively reshaping the social graph layout but in reality, it assists the user to find a preferred positioning and direction in the high-dimensional space to look at the internal structure of the social graph layout, keeping it unmodified. A prototype implementation of the proposal called Social Viewpoint Finder is tested with about 70 social graphs and this paper reports four of the analysis results.
With the spread of computers to ordinary people, computer security is becoming increasingly impor... more With the spread of computers to ordinary people, computer security is becoming increasingly important. User authentication is one of the most important technologies for computer security. Although passwords are used in many personal computers, they are known to sometimes have problems. As an alternative to passwords, biometric authentication, such as fingerprint authentication and face recognition-based authentication, is becoming more widely used. In this paper, we propose a hand gesture-based method as a new kind of biometric authentication. It supports three-dimensional (3D) gestures that allow its user to move the user's hand without touching an input device. Using the motions of fingertips and finger joints as biometric data, the method improves the performance of authentication. Also, we propose seven 3D gestures that can be classified into three types. We implemented the method by using a 3D motion sensor called the Leap Motion controller. We present the results of an experiment that we conducted with nine participants to evaluate the method. For all the gestures, the true acceptance rates were more than 90 %, and the equal error rates were less than 4 %.
Newspapers and other media often describe particular topics over some periods by giving a series ... more Newspapers and other media often describe particular topics over some periods by giving a series of texts that introduces new information and corrects previous information. By analyzing such texts, we can understand how a topic changed over time and how the media treated it. However, analyzing such texts manually is time-consuming. To solve this problem, we propose a method for visualizing texts that describe a topic changing over time. For this purpose, we first generate an event information graph from such texts by using an exiting method. Then we transform it into two different graphs. The first graph shows changes in the topic that we obtain by separating the initial graph and comparing the resulting time-dependent graphs. The second graph depicts a summary of the topic that we obtain by extracting high-frequency words from the initial graph. The results of our experiment show that our method can visualize changes and important information described in the texts.
Constraints have been playing an important role in the user interface field since its infancy. A ... more Constraints have been playing an important role in the user interface field since its infancy. A prime use of constraints in this field is to automatically maintain geometric layouts of graphical objects. To facilitate the construction of constraint-based user interface applications, researchers have proposed various constraint satisfaction methods and constraint solvers. Most previous research has focused on either local propagation or linear constraints, excluding more general nonlinear ones. However, nonlinear geometric constraints are practically useful to various user interfaces, e.g., drawing editors and information visualization systems. In this paper, we propose a novel constraint solver called Chorus, which realizes various powerful nonlinear geometric constraints such as Euclidean geometric, non-overlapping, and graph layout constraints. A key feature of Chorus is its module mechanism that allows users to define new kinds of geometric constraints. Also, Chorus supports "soft" constraints with hierarchical strengths or preferences (i.e., constraint hierarchies). We describe its framework, algorithm, implementation, and experimental results.
Event-driven programming is a paradigm that is widely used in many fields. Processing is a set of... more Event-driven programming is a paradigm that is widely used in many fields. Processing is a set of programming languages and environments specialized in event-driven programming for interactive graphical applications. It provides only low-level event-handling functions, which imposes difficulty on novice programmers in programming complex behaviors. This paper proposes a method for unit-testing event-driven Processing programs. It allows writing testable Processing programs and test programs in Java. To demonstrate how it works, this paper presents case studies on testing whether mouse and key events are correctly handled.
In the education of introductory programming, people often adopt block-based visual programming l... more In the education of introductory programming, people often adopt block-based visual programming languages such as Scratch and Blockly that allow programmers to construct programs by placing visual blocks. A previous study showed that a block-based language was more effective than a text-based language in introductory programming education. However, even with such block-based languages, it is still necessary for novices to learn programming in traditional ways, for example, by hearing lectures, reading textbooks, or watching tutorial videos. In this paper, we propose a video game-like approach to supporting novices in learning programming. We introduce two concepts into a block-based programming system: one is a staging mechanism that allows novices to gradually obtain more complex means of programming; the other is an assistant chatbot that helps novices to gain knowledge of programming. We implemented the system by applying our approach to turtle graphics. We present results of the experiment that we conducted to evaluate our approach.
ABSTRACT Real-world information can often be expressed as a graph that consists of nodes and edge... more ABSTRACT Real-world information can often be expressed as a graph that consists of nodes and edges. Graphs are often effectively represented in a visual manner. To make visual representations of graphs easily available, researchers have proposed numerous techniques for automatic visualization of graphs [1]. An important class of graphs is the general undirected graph, which imposes no restrictions on its structure as well as having no directed edges. The forcedirected approach [1] is often adopted to visualize general undirected graphs, and works well for graphs with hundreds of nodes.
Voice adaptation is an interactive speech processing technique that allows the speaker to transmi... more Voice adaptation is an interactive speech processing technique that allows the speaker to transmit with a chosen target voice. We propose a novel method that is intended for dynamic scenarios, such as online video games, where the source speaker's and target speaker's data are nonaligned. This would yield massive improvements to immersion and experience by fully becoming a character, and address privacy concerns to protect against harassment by disguising the voice. With unaligned data, traditional methods, e.g., probabilistic models become inaccurate, while recent methods such as deep neural networks (DNN) require too substantial preparation work. Common methods require multiple subjects to be trained in parallel, which constraints practicality in productive environments. Our proposal trains a subject nonparallel into a voice profile used against any unknown source speaker. Prosodic data such as pitch, power and temporal structure are encoded into RGBA-colored frames used in a multi-objective optimization problem to adjust interrelated features based on color likeness. Finally, frames are smoothed and adjusted before output. The method was evaluated using Mean Opinion Score, ABX, MUSHRA, Single Ease Questions and performance benchmarks using two voice profiles of varying sizes and lastly discussion regarding game implementation. Results show improved adaptation quality, especially in a larger voice profile, and audience is positive about using such technology in future games.
International Journal on Software Tools for Technology Transfer, Mar 19, 2011
This paper presents a bounded model checking (BMC) tool called hydlogic for hybrid systems. It tr... more This paper presents a bounded model checking (BMC) tool called hydlogic for hybrid systems. It translates a reachability problem of a nonlinear hybrid system into a predicate logic formula involving arithmetic constraints, and checks the satisfiability of the formula based on a satisfiability modulo theories (SMT) method. We tightly integrate (i) an incremental SAT solver to enumerate the possible sets of constraints and (ii) an interval-based solver for hybrid constraint systems (HCSs) to solve the constraints described in the formulas. The HCS solver verifies the occurrence of a discrete change by enclosing continuous states that may cause the discrete change by a set of boxes. We adopt the existence property of a unique solution in the boxes computed by the HCS solver as (i) a proof of the reachability of a model, and (ii) a guide in the over-approximation refinement procedure. Our hydlogic implementation successfully handled several examples including those with nonlinear constraints.
In the last decade, with the development of multi-core workstations, the availability of GPGPU-en... more In the last decade, with the development of multi-core workstations, the availability of GPGPU-enhanced systems and the access to Grid platforms and supercomputers worldwide, Parallel Programming reached mainstream programming and appeared as a key issue in order to use in an efficient manner the computing power at hand. Search methods and combinatorial optimization techniques are not isolated from this phenomenon, as bigger computing power means the ability to attack more complex combinatorial problems. In the last years some experiments have been done to extend to parallel execution search methods such as Constraint Programming or SAT solving (Boolean satisfiability), and combinatorial optimization methods such as Local Search, Meta-heuristics and Brand & Bound. However these works have mostly been done for shared memory multi-core systems (i.e. with a few cores) or for small PC clusters (a few machines). The next challenge is to devise efficient techniques and algorithms for massively parallel computers with tens or hundreds of thousands of cores in the form of heterogeneous hybrid systems based on both multi-core processors and GPUs. We would like to provide a cross-community forum for researchers working on search methods (Constraint Solving, Artificial Intelligence, Logic Programming, SAT solving, etc.), combinatorial optimization methods (metaheuristics, local search, tabu search, evolutionary algorithms, ant colony optimization, particle swarm optimization, memetic algorithms, and other types of algorithms) and High Performance Computing (Grids, large PC clusters, massively parallel computers, GPGPUs) in order to tackle the challenge of efficient implementations on all kinds of parallel hardware: multi-core, GPU-based or heterogeneous massively parallel systems. This meeting is designed to be a forum for researchers willing to tackle those issues, in order to exchange ideas, theoretical frameworks, design of algorithms and methods, implementation issues, experimental results and further boost this growing area through cross-fertilization.
Graph drawing is an information visualization technology for illustrating relations between objec... more Graph drawing is an information visualization technology for illustrating relations between objects. Interactive graph drawing is often important since it is difficult to statically lay out complex graphs. For the interactive drawing of general undirected graphs, we have proposed the high-dimensional approach, which uses static graph layouts in high-dimensional spaces to dynamically find twodimensional layouts according to user interaction. Although the resulting interactive graph drawing method was found to be fast, other properties of it are not yet clear. In this paper, we analyze the high-dimensional approach to further explore its properties. Specifically, we perform the following two kinds of its analysis: (1) sensitivity analysis for investigating how the high-dimensional approach places graph nodes on the two-dimensional plane; (2) empirical analysis for examining the appropriateness of underlying graph layout methods. The results show that, as an underlying graph layout method, Kruskal and Seery's method based on Torgerson's multidimensional scaling method is more appropriate for the high-dimensional approach than other methods for computing graph layouts in high-dimensional spaces.
In formula-based fault localization methods, a program under test, which is unrolled to a certain... more In formula-based fault localization methods, a program under test, which is unrolled to a certain bound, is encoded in a trace formula (TF). The efficiency and precision of the fault localization algorithm depend highly on the way this formula is encoded. The full flow-sensitive TF can cover all potential root causes, but is usually large and scalability problems remain. We propose a new encoding, the hardened flow-sensitive trace formula (HFTF), which reduces the complexity of the formula but does not lose essential control flow graph (CFG) information required for localizing faults. The HFTF is constructed using a concolic execution method that generates both failing and successful executions and uses the coverage information from these executions to simplify the trace formula.
The paper tackles the problems of the “giant hairballs”, the dense and tangled structures often r... more The paper tackles the problems of the “giant hairballs”, the dense and tangled structures often resulting from visualization of large social graphs. Proposed is a high-dimensional rotation technique called AGI3D, combined with an ability to filter elements based on social centrality values. AGI3D is targeted for a high-dimensional embedding of a social graph and its projection onto 3D space. It allows the user to rotate the social graph layout in the high-dimensional space by mouse dragging of a vertex. Its high-dimensional rotation effects give the user an illusion that he/she is destructively reshaping the social graph layout but in reality, it assists the user to find a preferred positioning and direction in the high-dimensional space to look at the internal structure of the social graph layout, keeping it unmodified. A prototype implementation of the proposal called Social Viewpoint Finder is tested with about 70 social graphs and this paper reports four of the analysis results.
With the spread of computers to ordinary people, computer security is becoming increasingly impor... more With the spread of computers to ordinary people, computer security is becoming increasingly important. User authentication is one of the most important technologies for computer security. Although passwords are used in many personal computers, they are known to sometimes have problems. As an alternative to passwords, biometric authentication, such as fingerprint authentication and face recognition-based authentication, is becoming more widely used. In this paper, we propose a hand gesture-based method as a new kind of biometric authentication. It supports three-dimensional (3D) gestures that allow its user to move the user's hand without touching an input device. Using the motions of fingertips and finger joints as biometric data, the method improves the performance of authentication. Also, we propose seven 3D gestures that can be classified into three types. We implemented the method by using a 3D motion sensor called the Leap Motion controller. We present the results of an experiment that we conducted with nine participants to evaluate the method. For all the gestures, the true acceptance rates were more than 90 %, and the equal error rates were less than 4 %.
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Papers by Hiroshi Hosobe