Overfitting in Synthesis: Theory and Practice (Extended Version)

In syntax-guided synthesis (SyGuS), a synthesizer's goal is to automatically generate a program belonging to a grammar of possible implementations that meets a logical specification. We investigate a common limitation across state-of-the-art SyGuS tools that perform counterexample-guided inductive synthesis (CEGIS). We empirically observe that as the expressiveness of the provided grammar increases, the performance of these tools degrades significantly. We claim that this degradation is not only due to a larger search space, but also due to overfitting. We formally define this phenomenon and prove no-free-lunch theorems for SyGuS, which reveal a fundamental tradeoff between synthesizer performance and grammar expressiveness. A standard approach to mitigate overfitting in machine learning is to run multiple learners with varying expressiveness in parallel. We demonstrate that this insight can immediately benefit existing SyGuS tools. We also propose a novel single-threaded technique called hybrid enumeration that interleaves different grammars and outperforms the winner of the 2018 SyGuS competition (Inv track), solving more problems and achieving a $5\times$ mean speedup.Comment: 24 pages (5 pages of appendices), 7 figures, includes proofs of theorem

Computer Aided Verification

This open access two-volume set LNCS 11561 and 11562 constitutes the refereed proceedings of the 31st International Conference on Computer Aided Verification, CAV 2019, held in New York City, USA, in July 2019. The 52 full papers presented together with 13 tool papers and 2 case studies, were carefully reviewed and selected from 258 submissions. The papers were organized in the following topical sections: Part I: automata and timed systems; security and hyperproperties; synthesis; model checking; cyber-physical systems and machine learning; probabilistic systems, runtime techniques; dynamical, hybrid, and reactive systems; Part II: logics, decision procedures; and solvers; numerical programs; verification; distributed systems and networks; verification and invariants; and concurrency

Computer Aided Verification

This open access two-volume set LNCS 11561 and 11562 constitutes the refereed proceedings of the 31st International Conference on Computer Aided Verification, CAV 2019, held in New York City, USA, in July 2019. The 52 full papers presented together with 13 tool papers and 2 case studies, were carefully reviewed and selected from 258 submissions. The papers were organized in the following topical sections: Part I: automata and timed systems; security and hyperproperties; synthesis; model checking; cyber-physical systems and machine learning; probabilistic systems, runtime techniques; dynamical, hybrid, and reactive systems; Part II: logics, decision procedures; and solvers; numerical programs; verification; distributed systems and networks; verification and invariants; and concurrency

行動認識機械学習データセット収集のためのクラウドソーシングの研究

In this thesis, we propose novel methods to explore and improve crowdsourced data labeling for mobile activity recognition. This thesis concerns itself with the quality (i.e., the performance of a classification model), quantity (i.e., the number of data collected), and motivation (i.e., the process that initiates and maintains goal-oriented behaviors) of participant contributions in mobile activity data collection studies. We focus on achieving high-quality and consistent ground-truth labeling and, particularly, on user feedback’s impact under different conditions. Although prior works have used several techniques to improve activity recognition performance, differences to our approach exist in terms of the end goals, proposed method, and implementation. Many researchers commonly investigate post-data collection to increase activity recognition accuracy, such as implementing advanced machine learning algorithms to improve data quality or exploring several preprocessing ways to increase data quantity. However, utilizing post-data collection results is very difficult and time-consuming due to dirty data challenges for most real-world situations. Unlike those commonly used in other literature, in this thesis, we aim to motivate and sustain user engagement during their on-going-self-labeling task to optimize activity recognition accuracy. The outline of the thesis is as follows: In chapter 1 and 2, we briefly introduce the thesis work and literature review. In Chapter 3, we introduce novel gamified active learning and inaccuracy detection for crowdsourced data labeling for an activity recognition system (CrowdAct) using mobile sensing. We exploited active learning to address the lack of accurate information. We presented the integration of gamification into active learning to overcome the lack of motivation and sustained engagement. We introduced an inaccuracy detection algorithm to minimize inaccurate data. In Chapter 4, we introduce a novel method to exploit on-device deep learning inference using a long short-term memory (LSTM)-based approach to alleviate the labeling effort and ground truth data collection in activity recognition systems using smartphone sensors. The novel idea behind this is that estimated activities are used as feedback for motivating users to collect accurate activity labels. In Chapter 5, we introduce a novel on-device personalization for data labeling for an activity recognition system using mobile sensing. The key idea behind this system is that estimated activities personalized for a specific individual user can be used as feedback to motivate user contribution and improve data labeling quality. We exploited finetuning using a Deep Recurrent Neural Network (RNN) to address the lack of sufficient training data and minimize the need for training deep learning on mobile devices from scratch. We utilized a model pruning technique to reduce the computation cost of on-device personalization without affecting the accuracy. Finally, we built a robust activity data labeling system by integrating the two techniques outlined above, allowing the mobile application to create a personalized experience for the user. To demonstrate the proposed methods’ capability and feasibility in realistic settings, we developed and deployed the systems to real-world settings such as crowdsourcing. For the process of data labeling, we challenged online and self-labeling scenarios using inertial smartphone sensors, such as accelerometers. We recruited diverse participants and con- ducted the experiments both in a laboratory setting and in a semi-natural setting. We also applied both manual labeling and the assistance of semi-automated labeling. Addition- ally, we gathered massive labeled training data in activity recognition using smartphone sensors and other information such as user demographics and engagement. Chapter 6 offers a brief discussion of the thesis. In Chapter 7, we conclude the thesis with conclusion and some future work issues. We empirically evaluated these methods across various study goals such as machine learning and descriptive and inferential statistics. Our results indicated that this study enabled us to effectively collect crowdsourced activity data. Our work revealed clear opportunities and challenges in combining human and mobile phone-based sensing techniques for researchers interested in studying human behavior in situ. Researchers and practitioners can apply our findings to improve recognition accuracy and reduce unreliable labels by human users, increase the total number of collected responses, as well as enhance participant motivation for activity data collection.九州工業大学博士学位論文 学位記番号：工博甲第526号 学位授与年月日：令和3年6月28日1 Introduction|2 Related work|3 Achieving High-Quality Crowdsourced Datasets in Mobile Activity Recognition|4 On-Device Deep Learning Inference for Activity Data Collection|5 On-Device Deep Personalization for Activity Data Collection|6 Discussion|7 Conclusion九州工業大学令和3年

Tools and Algorithms for the Construction and Analysis of Systems

This open access two-volume set constitutes the proceedings of the 26th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2020, which took place in Dublin, Ireland, in April 2020, and was held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2020. The total of 60 regular papers presented in these volumes was carefully reviewed and selected from 155 submissions. The papers are organized in topical sections as follows: Part I: Program verification; SAT and SMT; Timed and Dynamical Systems; Verifying Concurrent Systems; Probabilistic Systems; Model Checking and Reachability; and Timed and Probabilistic Systems. Part II: Bisimulation; Verification and Efficiency; Logic and Proof; Tools and Case Studies; Games and Automata; and SV-COMP 2020

Women in Artificial intelligence (AI)

This Special Issue, entitled "Women in Artificial Intelligence" includes 17 papers from leading women scientists. The papers cover a broad scope of research areas within Artificial Intelligence, including machine learning, perception, reasoning or planning, among others. The papers have applications to relevant fields, such as human health, finance, or education. It is worth noting that the Issue includes three papers that deal with different aspects of gender bias in Artificial Intelligence. All the papers have a woman as the first author. We can proudly say that these women are from countries worldwide, such as France, Czech Republic, United Kingdom, Australia, Bangladesh, Yemen, Romania, India, Cuba, Bangladesh and Spain. In conclusion, apart from its intrinsic scientific value as a Special Issue, combining interesting research works, this Special Issue intends to increase the invisibility of women in AI, showing where they are, what they do, and how they contribute to developments in Artificial Intelligence from their different places, positions, research branches and application fields. We planned to issue this book on the on Ada Lovelace Day (11/10/2022), a date internationally dedicated to the first computer programmer, a woman who had to fight the gender difficulties of her times, in the XIX century. We also thank the publisher for making this possible, thus allowing for this book to become a part of the international activities dedicated to celebrating the value of women in ICT all over the world. With this book, we want to pay homage to all the women that contributed over the years to the field of AI

Time for change: a study of enrolment decision dynamics for admission into English secondary education

Cross-sectional studies suggest a prevalence of mental health problems from the age that children change to English secondary schools but there are few longitudinal appraisals of these issues and how enrolment policies influence psychological wellbeing. This research focuses on key factors linking competition for secondary schools and family responses to such challenges to determine enrolment policies that can sustain wellbeing longer-term. Integrated, model-based multimethodology was used in this urban, case-based study. Views were induced from multi-agency, expert practitioners to agree a system dynamics concept model. Parental decision-making behaviours were deduced by survey to understand key factors for model calibration. Dynamic system sensitivities were abduced from the simulation model before comparing long-term psychosocial impacts on children from expert, policy-support suggestions. Modelling demonstrates that two principal feedback loops influence family psychosocial systems when deciding secondary schools (parent-child wellbeing reinforcement plus knowledge of schools balancing parent concerns). Exogenous competition stressors on psychosocial systems can erode parent knowledge while testing student resolve. Competition guidance to remove risk-laden school options (league table comparison) before sequencing any remaining choices by profit (school visits), are not always used deciding urban secondary schools. Instead, families lacking experience can adopt decisive styles based on parent needs alone. Given autocratic leadership, child wellbeing rapidly deteriorates when student needs cannot be met by schools. Rather than ending student-selective entrance tests or raising knowledge of schools at visits, effective multi-agency support policy helps by increasing school choice debate frequency within families to address psychosocial system imbalances. The research makes a clear, three-way contribution to knowledge. Firstly, intrinsic case study theory is enhanced by data triangulation between induced, deduced and abduced research approaches. Secondly, the system dynamics discipline is strengthened by studying compulsory school enrolment. Finally, developing practice-based policy through multi-agency groups endorses cooperative rather than unilateral solutions, for helping change lives

Tools and Experiments for Software Security

The computer security problems that we face begin in computer programs that we write. The exploitation of vulnerabilities that leads to the theft of private information and other nefarious activities often begins with a vulnerability accidentally created in a computer program by that program's author. What are the factors that lead to the creation of these vulnerabilities? Software development and programming is in part a synthetic activity that we can control with technology, i.e. different programming languages and software development tools. Does changing the technology used to program software help programmers write more secure code? Can we create technology that will help programmers make fewer mistakes? This dissertation examines these questions. We start with the Build It Break It Fix It project, a security focused programming competition. This project provides data on software security problems by allowing contestants to write security focused software in any programming language. We discover that using C leads to memory safety issues that can compromise security. Next, we consider making C safer. We develop and examine the Checked C programming language, a strict super-set of C that adds types for spatial safety. We also introduce an automatic re-writing tool that can convert C code into Checked C code. We evaluate the approach overall on benchmarks used by prior work on making C safer. We then consider static analysis. After an examination of different parameters of numeric static analyzers, we develop a disjunctive abstract domain that uses a novel merge heuristic, a notion of volumetric difference, either approximated via MCMC sampling or precisely computed via conical decomposition. This domain is implemented in a static analyzer for C programs and evaluated. After static analysis, we consider fuzzing. We consider what it takes to perform a good evaluation of a fuzzing technique with our own experiments and a review of recent fuzzing papers. We develop a checklist for conducting new fuzzing research and a general strategy for identifying root causes of failure found during fuzzing. We evaluate new root cause analysis approaches using coverage information as inputs to statistical clustering algorithms

Process Mining Handbook

This is an open access book. This book comprises all the single courses given as part of the First Summer School on Process Mining, PMSS 2022, which was held in Aachen, Germany, during July 4-8, 2022. This volume contains 17 chapters organized into the following topical sections: Introduction; process discovery; conformance checking; data preprocessing; process enhancement and monitoring; assorted process mining topics; industrial perspective and applications; and closing