Abstract
In this paper, we introduce a novel approach for rigorously verifying safety properties of state machine specifications. Our method leverages an auto-active verifier and centers around the use of action functions annotated with contracts. These contracts facilitate inductive invariant checking, ensuring correctness during system execution. Our approach is further supported by the Why3-do library, which extends the Why3 tool's capabilities to verify concurrent and distributed algorithms using state machines. Two distinctive features of Why3-do are: (i) it supports specification refinement through refinement mappings, enabling hierarchical reasoning about distributed algorithms; and (ii) it can be easily extended to make verifying specific classes of systems more convenient. In particular, the library contains models allowing for message-passing algorithms to be described with programmed handlers, assuming different network semantics. A gallery of examples, all verified with Why3 using SMT solvers as proof tools, is also described in the paper. It contains several auto-actively verified concurrent and distributed algorithms, including the Paxos consensus algorithm.

Abstract

Abstract
The growing integration of Artificial Intelligence (AI) into interactive systems presents unique challenges and opportunities for Human-Computer Interaction (HCI) and User Experience (UX). While AI can enhance usability and provide novel interaction paradigms, it also raises concerns related to transparency, control, and user trust. This workshop seeks to bring together researchers and practitioners to discuss state-of-the-art engineering methods that support HCI and UX in AI-driven systems. By fostering interdisciplinary collaboration, we aim to identify key challenges, share best practices, and develop a roadmap for future research in this critical area.

Abstract
Safety-critical interactive systems pose design and evaluation challenges that go beyond usability. The safety of the system (i.e. the guarantee that it does not reach an undesirable or incorrect state) is also a relevant consideration. Traditional user-centred approaches (UCD) lack the rigour and thoroughness needed to address safety, and formal verification arises as a possible solution. Applying formal verification to a safety-critical interactive system design encompasses developing a model, expressing and verifying properties, and analysing the verification results. In the case of model checking, properties are typically expressed in temporal logic. This creates a gap between the languages used in UCD and the languages used for formal verification. Creating temporal logic properties manually requires expertise in formal methods and can be both time-consuming and error-prone. This paper explores how a patterns-based approach can be used to support the specification of properties in a natural language-based style. A prototype implementation of the approach is evaluated through a user study, and the results of this evaluation are discussed.

Abstract
A key feature of model finding techniques allows users to enumerate and explore alternative solutions. However, it is challenging to guarantee that the generated instances are relevant to the user, representing effectively different scenarios. This challenge is exacerbated in quantitative modelling, where one must consider both the qualitative, structural part of a model, and the quantitative data on top of it. This results in a search space of possibly infinite candidate solutions, often infinitesimally similar to one another. Thus, research on instance enumeration in qualitative model finding is not directly applicable to the quantitative context, which requires more sophisticated methods to navigate the solution space effectively. The main goal of this paper is to explore a generic approach for navigating quantitative solution spaces and showcase different iteration operations, aiming to generate instances that differ considerably from those previously seen and promote a larger coverage of the search space. Such operations are implemented in QAlloy - a quantitative extension to Alloy - on top of Max-SMT solvers, and are evaluated against several examples ranging, in particular, over the integer and fuzzy domains.

Abstract
The staggered model is a recent, very general variant of discrete-time quantum walks which, avoiding the use of a coin to direct the walker evolution, explores the underlying graph structure to build an evolution operator based on local unitaries induced by adjacent vertices. Optimising their implementation to increase resilience to decoherence phenomena motivates their analysis with the ZX-calculus. The whole optimisation can be seen as a graph reconfiguration process along which the original circuit is rewrote, significantly reducing the number of (expensive) gates used. The exercise identified an underlying pattern leading to an alternative, potentially more efficient evolution operator.