Abstract
The structure of a reactive transition system can to be modified on the fly by e.g. removing, reversing or adding new transitions. The topic has been studied by D. Gabbay and his collaborators in different contexts. In this paper we take their work a step further, introducing a suitable notion of bisimulation and obtaining a Hennessy-Milner theorem with respect to a hybrid logic in which transition properties can be expressed. Our motivation is to provide a characterisation of equivalence for such systems in order to exploit their possible roles in the formal description of software connectors in Reo, either from a behavioural (semantic) or spatial (syntactic) point of view.

Abstract
Quantum algorithmics is emerging as a hot area of research, with the potential to have groundbreaking impacts on many different fields. The benefits come at a high price, however: quantum programming is hard and finding new quantum algorithms is far from straightforward. This area of research may greatly benefit from mathematical foundations and calculi, capable of supporting algorithm development and analysis. The Quantum Algorithmics Agenda at QuantaLab is contributing by seeking a suitable semantics-calculus-logic trilogy for quantum computation.

Abstract
We introduce HHL, a hierarchical variant of hybrid logic. We study first order correspondence results and prove a Hennessy-Milner like theorem relating (hierarchical) bisimulation and modal equivalence for HHL. Combining hierarchical transition structures with the ability to refer to specific states at different levels, this logic seems suitable to express and verify properties of hierarchical transition systems, a pervasive semantic structure in Computer Science.

Abstract
In the context of digital transformation by governments, the public sector and other organizations, many information is moving to digital platforms. Chatbots and similar question-answering systems are becoming popular to answer information queries, opposed to browsing online repositories or webpages. State-of-the-art approaches for these systems may be laborious to implement, hard to train and maintain, and also require a high level of expertise. This work explores the definition of a generic framework to systematically build question-answering systems. A sandbox implementation of this framework enables the deployment of turnkey systems, directly from already existing collections of documents. These systems can then be used to provide a question-answering system communication channel to enrich the organization digital presence.

Abstract
Kleene algebra with tests (KAT) was introduced as an algebraic structure to model and reason about classic imperative programs, i.e. sequences of discrete transitions guarded by Boolean tests. This paper introduces two generalisations of this structure able to express programs as weighted transitions and tests with outcomes in non necessarily bivalent truth spaces: graded Kleene algebra with tests (GKAT) and a variant where tests are also idempotent (I-GKAT). In this context, and in analogy to Kozen's encoding of Propositional Hoare Logic (PHL) in KAT we discuss the encoding of a graded PHL in I-GKAT and of its while-free fragment in GKAT. Moreover, to establish semantics for these structures four new algebras are defined: FSET(T), FREL(K,T) and FLANG(K,T) over complete residuated lattices K and T, and M (n, A) over a GKAT or I-GKAT A. As a final exercise, the paper discusses some program equivalence proofs in a graded context.

Abstract
Dynamic logic is a powerful framework for reasoning about imperative programs. This paper extends previous work [9] on the systematic generation of dynamic logics from the propositional to the equational case, to capture ‘full-fledged’ imperative programs. The generation process is parametric on a structure specifying a notion of ‘weight’ assigned to programs. The paper introduces also a notion of bisimilarity on models of the generated logics, which is shown to entail modal equivalence with respect to the latter.