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Improving the performance and functionality of contemporary debugging tools is essential to alleviate the debugging task. This dissertation aims at narrowing the gap between current capabilities of debugging tools and industry requirements by improving two important debugging techniques: error trace compaction and automated debugging. Error trace compaction leverages incremental SAT and heuristics to reduce the number of clock cycles required to observe a failure in an error trace. The technique presented reduces the length of the error trace to a minimum while improving performance by 8× compared to a previous technique. The second contribution uses maximum satisfiability to enhance the functionality and performance of automated debuggers. The method proposed can identify where in the design the bug is located and when in the error trace the bug is excited. Compared to a competitive SAT-based approach, our formulation produces problems that are 80% smaller and that can be solved 4.5x faster.

Improving the performance and functionality of contemporary debugging tools is essential to alleviate the debugging task. This dissertation aims at narrowing the gap between current capabilities of debugging tools and industry requirements by improving two important debugging techniques: error trace compaction and automated debugging. Error trace compaction leverages incremental SAT and heuristics to reduce the number of clock cycles required to observe a failure in an error trace. The technique presented reduces the length of the error trace to a minimum while improving performance by 8× compared to a previous technique. The second contribution uses maximum satisfiability to enhance the functionality and performance of automated debuggers. The method proposed can identify where in the design the bug is located and when in the error trace the bug is excited. Compared to a competitive SAT-based approach, our formulation produces problems that are 80% smaller and that can be solved 4.5x faster.

Action Semantics is a framework for defining the semantics of languages. It is intended to be accessible to a wider audience of Computer Scientists than traditional semantics frameworks (such as Denotational Semantics). There has been little work carried out to date on the techniques required to define object-oriented languages with Action Semantics. The work presented in this thesis examines four potential approaches to defining the Action Semantics of object-oriented languages. In order to illustrate the four approaches a simple language EIL (Example Inheritance Language) is given, and described using these four approaches. The language Smalltalk-80 has been selected for a case study of a practical application of one of the techniques described above. It is important to be able to relate Action Semantics definitions of object-oriented languages to similar definitions given in other frameworks. It is described how this can be achieved. An example is given for the Action Semantics and Denotational Semantics of Smalltalk. This thesis concludes that it is feasible to produce Action Semantics definitions of object-oriented languages.

The increased adoption and deployment of cyber-physical systems in critical infrastructure in recent years have led to challenging questions about safety and reliability. These systems usually operate in uncertain environments and are required to satisfy a broad spectrum of specifications. Thus, automated tools are necessary to alleviate the need for manual design and proof of their correct behaviors. This thesis studies mathematical and computational frameworks to design correct and optimal control strategies for discrete-time and continuous-time systems with temporal and spatial specifications. Signal Temporal Logic (STL) is employed as a rich and expressive language to impose temporal constraints and deadlines on system performance. The first part of the thesis introduces a novel quantitative semantics for STL that improves the evaluation of temporal logic specifications. Furthermore, an extension of STL, called Weighted Signal Temporal Logic (wSTL), is defined in order to formalize satisfaction priorities of multiple specifications and time preferences in a high-level specification. Learning-based frameworks are proposed to infer quantitative semantics, and satisfaction priorities and preferences from data. The second part develops optimization frameworks to determine control strategies enforcing the satisfaction of wSTL specifications by different classes of systems. Mixed-integer programming and gradient-based optimization techniques are studied to solve the control synthesis problem. Further evaluation and optimization algorithms are presented based on Control Barrier Functions to guarantee continuous-time satisfaction of safety-critical specifications in a system. The third part of this thesis focuses on utilizing STL to express spatio-temporal specifications that are widely used in networks of locally interacting dynamical systems. Machine learning techniques are used to derive spatio-temporal quantitative semantics, which is employed in automated frameworks for evaluation and synthesis of complex spatial and temporal properties. Case studies illustrating the synthesis of spatio-temporal patterns in biological cell networks are presented.

This thesis presents a tool for the mechanical validation of formal software specifications. The tool is based on a novel approach to incremental validation. In this approach, small-scale aspects of a specification are validated, as part of the stepwise refinement of a formal model. The incremental validation technique can be considered a form of "lightweight" model checking. This is in contrast to a "heavyweight" approach, wherein an entire large-scale model is validated en masse. The validation tool is part of a formal modeling and specification language (FMSL), used in software engineering instruction. A lightweight, incremental approach to validation is beneficial in this context. Such an approach can be used to elucidate specification concepts in a step-by-step manner. A heavy-weight approach to model checking is more difficult to use in this way. The FMSL model checker has itself been validated by evaluating portions of a medium-scale specification example. The example has been used in software engineering courses for a number of years, but has heretofore been validated only by human inspection. Evidence for the utility of the validation tool is provided by its performance during the example validation. In particular, use of the tool led to the discovery of a specification flaw that had gone undiscovered by manual validation alone.