Mechanical and Modular Verification Condition Generation for Object-Based Software

The foundational goal of this work is the development of mechanizable proof rules and a verification condition generator based on those rules for modern software. The verification system will be modular so that it is possible to verify the implementation of a component relying upon only the specifications of underlying components that are reused. The system must enable full behavioral verification. The proof rules used to generate verification conditions (VCs) of correctness must be amenable to automation. While automation requires software developers to annotate implementations with assertions, it should not require assistance in the proofs. This research has led to a VC generator that realizes these goals. The VC generator has been applied to a range of benchmarks to show the viability of verified components. It has been used in classrooms at multiple institutions to teach reasoning principles. A fundamental problem in computing is the inability to show that a software system behaves as required. Modern software systems are composed of numerous software components. The fundamental goal of this work is to verify each independently in a modular fashion, resulting in full behavioral verification and providing an assurance that components meet their specifications and can be used with confidence to build verified software systems. Of course, to be practical, such a system must be mechanical. Although the principles of verification have existed for decades, the basis for a practical verification system for modern software components has remained elusive

The Structure of Sensorimotor Explanation

The sensorimotor theory of vision and visual consciousness is often described as a radical alternative to the computational and connectionist orthodoxy in the study of visual perception. However, it is far from clear whether the theory represents a significant departure from orthodox approaches or whether it is an enrichment of it. In this study, I tackle this issue by focusing on the explanatory structure of the sensorimotor theory. I argue that the standard formulation of the theory subscribes to the same theses of the dynamical hypothesis and that it affords covering-law explanations. This however exposes the theory to the mere description worry and generates a puzzle about the role of representations. I then argue that the sensorimotor theory is compatible with a mechanistic framework, and show how this can overcome the mere description worry and solve the problem of the explanatory role of representations. By doing so, it will be shown that the theory should be understood as an enrichment of the orthodoxy, rather than an alternative

Changing identities, changing landscapes: The long term dynamics of human - land relations in the ASPRE, Roussillon

This research seeks to explore the complexity of human - land relations in the Aspre, with respect to land degradation. It is argued that in human modified environments, such as this Mediterranean - Pyrenean borderland, nature and culture cannot be meaningfully studied apart. Consequently issues of land degradation must be situated within the broader context of socio-natural interaction. Such a study cannot be approached solely from a natural or social science perspective; what is required, and what has been developed in this research, is a transdisciplinary methodology whereby natural phenomena are situated within their historical and socio-cultural context. Central to that context is the need to position the system within a long term evolutionary dynamic, thus allowing us to view the system in process, rather than as a synchronic present day snapshot. Within this 'longue duree' temporal and spatial scales are seen to be critical. It is argued that land degradation is at root a perceptual issue, thus perception and cognition are seen as critically important in this study. The core field work acts to expose both the physical and social identities of the Aspre, and the multiple perceptions of land degradation held by its inhabitants. The research identifies a series of 'perceptual filters' through which the environment of the Aspre is experienced, and by means of which meaning is negotiated. The recognition of the multiple environmental perceptions and plural rationalities is of crucial importance when contemplating the possible future pathways open to the Aspre, with respect to sustainable futures. What emerges from this research is a redefinition of land degradation in the Aspre, from that of a purely physical issue, to the realization that what we are dealing with are changing social identities within changing landscapes