Debugging complex systems is a crucial yet time-consuming task. This paper presents the use of automata learning and testing techniques to obtain concise and informative bug descriptions. We introduce the concepts of Failure Explanations (FE), Eventual Failure Explanations (EFE), and Early Detection (ED) to provide meaningful summaries of failing behavior patterns. By factoring out irrelevant information and focusing on essential test patterns, our approach aims to enhance bug detection and understanding. We evaluate our methods using various test patterns and real-world benchmarks, demonstrating their effectiveness in producing compact and informative bug descriptions.

Reactive synthesis is an automated procedure to obtain a correct-by-construction reactive system from its temporal logic specification. Two of the main challenges in bringing reactive synthesis to practice are its very high worst-case complexity and the difficulty of writing declarative specifications using basic LTL operators. To address the first challenge, researchers have suggested the GR(1) fragment of LTL, which has an efficient poly-nomial time symbolic synthesis algorithm. To address the second challenge, specification languages include higher-level constructs that aim at allowing engineers to write succinct and readable specifications. One such construct is the triggers operator, as supported, e.g., in the Property Specification Language (PSL). In this work we introduce triggers into specifications for reactive synthesis. The effectiveness of our contribution relies on a novel encoding of regular expressions using symbolic finite automata (SFA) and on a novel semantics for triggers that, in contrast to PSL triggers, admits an efficient translation into GR(1). We show that our triggers are expressive and succinct, and prove that our encoding is optimal. We have implemented our ideas on top of the Spectra language and synthesizer. We demonstrate the usefulness and effectiveness of using triggers in specifications for synthesis, as well as the challenges involved in using them, via a study of more than 300 triggers written by undergraduate students who participated in a project class on writing specifications for synthesis. To the best of our knowledge, our work is the first to introduce triggers into specifications for reactive synthesis.

Reactive synthesis is an automated procedure to obtain a correct-by-construction reactive system from its temporal logic specification. GR(1) is an expressive fragment of LTL that enables efficient synthesis and has been recently used in different contexts and application domains. In this paper we investigate the dynamic-update problem for GR(1): updating the behavior of an already running synthesized controller such that it would safely and dynamically, without stopping, start conforming to a modified, up-to-date specification. We formally define the dynamic-update problem and present a sound and complete solution that is based on the computation of a bridge-controller. We implemented the work in the Spectra synthesis and execution environment and evaluated it over benchmark specifications. The evaluation shows the efficiency and effectiveness of using dynamic updates. The work advances the state-of-the-art in reactive synthesis and opens the way to its use in application domains where dynamic updates are a necessary requirement.

Abstract In the Adapter Design Pattern, a programmer implements a Target interface by constructing an Adapter that accesses an existing Adaptee code. In this work, we present a reactive synthesis interpretation to the adapter design pattern, wherein an algorithm takes an Adaptee and a Target transducers, and the aim is to synthesize an Adapter transducer that, when composed with the Adaptee, generates a behavior that is equivalent to the behavior of the Target. One use of such an algorithm is to synthesize controllers that achieve similar goals on different hardware platforms. While this problem can be solved with existing synthesis algorithms, current state-of-the-art tools fail to scale. To cope with the computational complexity of the problem, we introduce a special form of specification format, called Separated GR(k), which can be solved with a scalable synthesis algorithm but still allows for a large set of realistic specifications. We solve the realizability and the synthesis problems for Separated GR(k), and show how to exploit the separated nature of our specification to construct better algorithms, in terms of time complexity, than known algorithms for GR(k) synthesis. We then describe a tool, called SGR(k), that we have implemented based on the above approach and show, by experimental evaluation, how our tool outperforms current state-of-the-art tools on various benchmarks and test-cases.

Abstract Reactive synthesis is an automated procedure to obtain a correct-by-construction reactive system from its temporal logic specification. GR(1) is an expressive assume-guarantee fragment of LTL that enables efficient synthesis and has been recently used in different contexts and application domains. A common form of providing system's requirements is through use cases, which are existential in nature. However, GR(1), as a fragment of LTL, is limited to universal properties. In this paper we introduce GR(1)*, which extends GR(1) with existential guarantees. We show that GR(1)* is strictly more expressive than GR(1) as it enables the expression of guarantees that are inexpressible in LTL. We solve the realizability problem for GR(1)* and present a symbolic strategy construction algorithm for GR(1)* specifications. Importantly, in comparison to GR(1), GR(1)* remains efficient: the time complexity of our realizability checking and synthesis procedures for GR(1)* is identical to the time complexity of the known corresponding procedures for GR(1).