Unifying Semantic Foundations for Automated Verification Tools in Isabelle/UTP

The growing complexity and diversity of models used for engineering dependable systems implies that a variety of formal methods, across differing abstractions, paradigms, and presentations, must be integrated. Such an integration requires unified semantic foundations for the various notations, and co-ordination of a variety of automated verification tools. The contribution of this paper is Isabelle/UTP, an implementation of Hoare and He’s Unifying Theories of Programming, a framework for unification of formal semantics. Isabelle/UTP permits the mechanisation of computational theories for diverse paradigms, and their use in constructing formalised semantics. These can be further applied in the development of verification tools, harnessing Isabelle’s proof automation facilities. Several layers of mathematical foundations are developed, including lenses to model variables and state spaces as algebraic objects, alphabetised predicates and relations to model programs, algebraic and axiomatic semantics, proof tools for Hoare logic and refinement calculus, and UTP theories to encode computational paradigms

Critical indirectness as a design approach in participatory practice: Spatialities of multivocal estrangement in three engagements with public cultural institutions around participatory projects in Gothenburg

Contributing across the domains of open transdisciplinary inquiry and transdisciplinary- and practice-oriented architectural and urbanism research engaging critically with participation in urban contexts, this research proposes critical indirectness as a multivocal design approach in participatory practice, developed through conceptual-analytical inquiry into three cases involving engagements between external art and design practitioners and public cultural institutions around participatory projects in Gothenburg. It joins with calls for art and design practitioners\u27 greater engagement with public sector institutions as way of working towards a more durable and wider impact, with calls to model a more de-centered \u27urban-combinatory\u27 practice on the plurality, hybridity, discontinuities, and contingencies of the contemporary city, and with calls for more multiple, contradictory approaches. Its methodological approach, open transdisciplinary turn-taking, likewise pursued these aims via alternating engagements between institutional and external actors, my own and others\u27 practices, and theory from multiple fields. The primary aim is to explore how art and design practitioners (including researchers and institutional actors) can develop greater capacity to critically wayfind within the complexities of engagements with public cultural institutions in and around participatory processes. This is supported by two interrelated inquiries, the first reworks monovocal understandings of participation, critique, institutions, and actors as multivocal—simultaneously collective, complex, and involving actors\u27 critical and creative trajectories of agency. The second conceptualizes multivocal relations as having their own critical efficacy through potentially estranging effects, which can be both reflexively perceived by practitioners and furthered by design. These two inquiries combine in the use, in case analyses, of alternating voices, transversing voices, and wavering voices—conceptual-analytical lenses enabling focus on the critical and creative potentials of spatialities of multivocal estrangement generated by differential interrelations between \u27voices\u27

Hybrid Relations in Isabelle/UTP

We describe our UTP theory of hybrid relations, which extends the relational calculus with continuous variables and differential equations. This enables the use of UTP in modelling and verification of hybrid systems, supported by our mechanisation in Isabelle/UTP. The hybrid relational calculus is built upon the same foundation as the UTP’s theory of reactive processes, which is accomplished through a generalised trace algebra and a model of piecewise-continuous functions. From this foundation, we give semantics to hybrid programs, including ordinary differential equations and preemption, and show how the theory can be used to reason about sequential hybrid systems