Classes of Terminating Logic Programs

Termination of logic programs depends critically on the selection rule, i.e. the rule that determines which atom is selected in each resolution step. In this article, we classify programs (and queries) according to the selection rules for which they terminate. This is a survey and unified view on different approaches in the literature. For each class, we present a sufficient, for most classes even necessary, criterion for determining that a program is in that class. We study six classes: a program strongly terminates if it terminates for all selection rules; a program input terminates if it terminates for selection rules which only select atoms that are sufficiently instantiated in their input positions, so that these arguments do not get instantiated any further by the unification; a program local delay terminates if it terminates for local selection rules which only select atoms that are bounded w.r.t. an appropriate level mapping; a program left-terminates if it terminates for the usual left-to-right selection rule; a program exists-terminates if there exists a selection rule for which it terminates; finally, a program has bounded nondeterminism if it only has finitely many refutations. We propose a semantics-preserving transformation from programs with bounded nondeterminism into strongly terminating programs. Moreover, by unifying different formalisms and making appropriate assumptions, we are able to establish a formal hierarchy between the different classes.Comment: 50 pages. The following mistake was corrected: In figure 5, the first clause for insert was insert([],X,[X]

Semantic Analyses to Detect and Localize Software Regression Errors

Ph.DDOCTOR OF PHILOSOPH

Creating architecture for a digital information system leveraging virtual environments

Abstract. The topic of the thesis was the creation of a proof of concept digital information system, which utilizes virtual environments. The focus was finding a working design, which can then be expanded upon. The research was conducted using design science research, by creating the information system as the artifact. The research was conducted for Nokia Networks in Oulu, Finland; in this document referred to as “the target organization”. An information system is a collection of distributed computing components, which come together to create value for an organization. Information system architecture is generally derived from enterprise architecture, and consists of a data-, technical- and application architectures. Data architecture outlines the data that the system uses, and the policies related to its usage, manipulation and storage. Technical architecture relates to various technological areas, such as networking and protocols, as well as any environmental factors. The application architecture consists of deconstructing the applications that are used in the operations of the information system. Virtual reality is an experience, where the concepts of presence, autonomy and interaction come together to create an immersive alternative to a regular display-based computer environment. The most typical form of virtual reality consists of a headmounted device, controllers and movement-tracking base stations. The user’s head- and body movement can be tracked, which changes their position in the virtual environment. The proof-of-concept information system architecture used a multi-server -based solution, where one central physical server hosted multiple virtual servers. The system consisted of a website, which was the knowledge-center and where a client software could be downloaded. The client software was the authorization portal, which determined the virtual environments that were available to the user. The virtual reality application included functionalities, which enable co-operative, virtualized use of various Nokia products, in immersive environments. The system was tested in working situations, such as during exhibitions with customers. The proof-of-concept system fulfilled many of the functional requirements set for it, allowing for co-operation in the virtual reality. Additionally, a rudimentary model for access control was available in the designed system. The shortcomings of the system were related to areas such as security and scaling, which can be further developed by introducing a cloud-hosted environment to the architecture

Fundamental Approaches to Software Engineering

This open access book constitutes the proceedings of the 23rd International Conference on Fundamental Approaches to Software Engineering, FASE 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 23 full papers, 1 tool paper and 6 testing competition papers presented in this volume were carefully reviewed and selected from 81 submissions. The papers cover topics such as requirements engineering, software architectures, specification, software quality, validation, verification of functional and non-functional properties, model-driven development and model transformation, software processes, security and software evolution

Localizing and Explaining Reasons for Non-Terminating Logic Programs With Failure-Slices

We present a slicing approach for analyzing logic programs with respect to non-termination. The notion of a failure-slice is presented which is an executable reduced fragment of the program. Each failureslice represents a necessary termination condition for the program. If a failure-slice does not terminate it can be used as an explanation for the non-termination of the whole program. To effectively determine useful failure-slices we combine a constraint based static analysis with the dynamic execution of actual slices. The current approach has been integrated into a programming environment for beginners. Further, we show how our approach can be combined with traditional techniques of termination analysis

Fundamental Approaches to Software Engineering

This open access book constitutes the proceedings of the 24th International Conference on Fundamental Approaches to Software Engineering, FASE 2021, which took place during March 27–April 1, 2021, and was held as part of the Joint Conferences on Theory and Practice of Software, ETAPS 2021. The conference was planned to take place in Luxembourg but changed to an online format due to the COVID-19 pandemic. The 16 full papers presented in this volume were carefully reviewed and selected from 52 submissions. The book also contains 4 Test-Comp contributions

The 1992 Goddard Conference on Space Applications of Artificial Intelligence

The purpose of this conference is to provide a forum in which current research and development directed at space applications of artificial intelligence can be presented and discussed. The papers fall into the following areas: planning and scheduling, control, fault monitoring/diagnosis and recovery, information management, tools, neural networks, and miscellaneous applications

Hardware-Assisted Processor Tracing for Automated Bug Finding and Exploit Prevention

The proliferation of binary-only program analysis techniques like fuzz testing and symbolic analysis have lead to an acceleration in the number of publicly disclosed vulnerabilities. Unfortunately, while bug finding has benefited from recent advances in automation and a decreasing barrier to entry, bug remediation has received less attention. Consequently, analysts are publicly disclosing bugs faster than developers and system administrators can mitigate them. Hardware-supported processor tracing within commodity processors opens new doors to observing low-level behaviors with efficiency, transparency, and integrity that can close this automation gap. Unfortunately, several trade-offs in its design raise serious technical challenges that have limited widespread adoption. Specifically, modern processor traces only capture control flow behavior, yield high volumes of data that can incur overhead to sift through, and generally introduce a semantic gap between low-level behavior and security relevant events. To solve the above challenges, I propose control-oriented record and replay, which combines concrete traces with symbolic analysis to uncover vulnerabilities and exploits. To demonstrate the efficacy and versatility of my approach, I first present a system called ARCUS, which is capable of analyzing processor traces flagged by host-based monitors to detect, localize, and provide preliminary patches to developers for memory corruption vulnerabilities. ARCUS has detected 27 previously known vulnerabilities alongside 4 novel cases, leading to the issuance of several advisories and official developer patches. Next, I present MARSARA, a system that protects the integrity of execution unit partitioning in data provenance-based forensic analysis. MARSARA prevents several expertly crafted exploits from corrupting partitioned provenance graphs while incurring little overhead compared to prior work. Finally, I present Bunkerbuster, which extends the ideas from ARCUS and MARSARA into a system capable of proactively hunting for bugs across multiple end-hosts simultaneously, resulting in the discovery and patching of 4 more novel bugs.Ph.D