Clinical psychological science : a journal of the Association for Psychological Science, 2015
Depression is a global health problem requiring treatment innovation. Targeting neglected cogniti... more Depression is a global health problem requiring treatment innovation. Targeting neglected cognitive aspects may provide a useful route. We tested a cognitive-training paradigm using positive mental imagery (imagery cognitive bias modification, imagery CBM), developed via experimental psychopathology studies, in a randomized controlled trial. Training was delivered via the Internet to 150 individuals with current major depression. Unexpectedly, there was no significant advantage for imagery CBM compared with a closely matched control for depression symptoms as a whole in the full sample. In exploratory analyses, compared with the control, imagery CBM significantly improved anhedonia over the intervention and improved depression symptoms as a whole for those participants with fewer than five episodes of depression and those who engaged to a threshold level of imagery. Results suggest avenues for improving imagery CBM to inform low-intensity treatment tools for depression. Anhedonia ma...
11th IEEE International Conference on Engineering of Complex Computer Systems (ICECCS'06), 2006
This paper shows how ideas from a combination of formal techniques can be used to enable the auto... more This paper shows how ideas from a combination of formal techniques can be used to enable the auto-matic generation of databases from precise object mod-els. It explores how the specification of an object database design can be formalised in terms of method preconditions, method ...
Model-driven engineering involves the automatic generation of software artifacts from models of s... more Model-driven engineering involves the automatic generation of software artifacts from models of structure and functionality. The use of models as 'source code'has implications for the notions of composition and refinement employed in the modelling language. This paper explores those implications in the context of object-oriented design: establishing a necessary and sufficient condition for a collection of classes to be treated as a component, identifying an appropriate notion of refinement for the generation process, and ...
Model-driven engineering is the generation of software artefacts from abstract models. This is ac... more Model-driven engineering is the generation of software artefacts from abstract models. This is achieved through transformations that encode domain knowledge and implementation strategies. The same transformations can be used to produce quite different systems, or to produce successive versions of the same system. A model-driven approach can thus reduce the cost of development. It can also reduce the cost of verification: if the transformations are shown or assumed to be correct, each new system or version can be verified in terms of its model, rather than its implementation. This paper introduces an approach to modeldriven engineering that is particularly suited to the development of critical information systems. The language of the models, and the language of the transformations, are amenable to formal analysis. The transformation strategy, and the associated development methodology, are designed to preserve systems integrity and availability. then the dependency upon other processes is reduced; expensive, manual effort can be focused upon surrounding issues of management and validation.
Many approaches to software specification and design make use of invariants: constraints whose tr... more Many approaches to software specification and design make use of invariants: constraints whose truth is preserved under operations on a system or component. Object modelling involves the definition of association invariants: constraints upon the sets of links corresponding to particular associations, most often concerning type, multiplicity, or symmetry. This paper shows how the definitions of operations may be extended to take account of association invariants, so that they may be properly considered when the operations are implemented. It introduces a formal, object-based modelling notation in which the process of extension and implementation, and thus the maintenance of association invariants, can be automated, making it easier to produce correct implementations of an object-oriented design.
Abstract This paper reports upon ten years of experience in the development and application of mo... more Abstract This paper reports upon ten years of experience in the development and application of model-driven technology. The technology in question was inspired by work on formal methods: in particular, by the B toolkit. It was used in the development of a number of information systems, all of which were successfully deployed in real world situations.
Electronic Notes in Theoretical Computer Science, 2008
This paper shows how a domain-specific semantics for object models can be used to support the dev... more This paper shows how a domain-specific semantics for object models can be used to support the development of transformations that reflect a particular implementation strategy. The semantics captures model constraints and domain assumptions in terms of abstract data types, and a transformation is correct if and only if it corresponds to a data refinement. The transformations represent development steps, involving the completion of method descriptions, and validity checks, addressing issues of definedness and consistency. The paper shows how compositions of transformations may be used for the automatic generation of working systems from formal, object-oriented designs.
Electronic Notes in Theoretical Computer Science, 2007
This paper explains precisely how a declarative method language, based upon the formal notations ... more This paper explains precisely how a declarative method language, based upon the formal notations of Z and B, can be used as a basis for automatic code generation. The language is used to describe the intended effect of operations, or methods, upon the components of an object model; each method is defined by a pair of predicates-pre-and post-conditions. Following the automatic incorporation of model invariants, including those arising from class associations, these predicates are extended-again, automatically-to address issues of consistency, definition, and dependency, before being transformed into imperative programs. The result is a formal method for transforming object models into complete, working systems.
Clinical psychological science : a journal of the Association for Psychological Science, 2015
Depression is a global health problem requiring treatment innovation. Targeting neglected cogniti... more Depression is a global health problem requiring treatment innovation. Targeting neglected cognitive aspects may provide a useful route. We tested a cognitive-training paradigm using positive mental imagery (imagery cognitive bias modification, imagery CBM), developed via experimental psychopathology studies, in a randomized controlled trial. Training was delivered via the Internet to 150 individuals with current major depression. Unexpectedly, there was no significant advantage for imagery CBM compared with a closely matched control for depression symptoms as a whole in the full sample. In exploratory analyses, compared with the control, imagery CBM significantly improved anhedonia over the intervention and improved depression symptoms as a whole for those participants with fewer than five episodes of depression and those who engaged to a threshold level of imagery. Results suggest avenues for improving imagery CBM to inform low-intensity treatment tools for depression. Anhedonia ma...
11th IEEE International Conference on Engineering of Complex Computer Systems (ICECCS'06), 2006
This paper shows how ideas from a combination of formal techniques can be used to enable the auto... more This paper shows how ideas from a combination of formal techniques can be used to enable the auto-matic generation of databases from precise object mod-els. It explores how the specification of an object database design can be formalised in terms of method preconditions, method ...
Model-driven engineering involves the automatic generation of software artifacts from models of s... more Model-driven engineering involves the automatic generation of software artifacts from models of structure and functionality. The use of models as 'source code'has implications for the notions of composition and refinement employed in the modelling language. This paper explores those implications in the context of object-oriented design: establishing a necessary and sufficient condition for a collection of classes to be treated as a component, identifying an appropriate notion of refinement for the generation process, and ...
Model-driven engineering is the generation of software artefacts from abstract models. This is ac... more Model-driven engineering is the generation of software artefacts from abstract models. This is achieved through transformations that encode domain knowledge and implementation strategies. The same transformations can be used to produce quite different systems, or to produce successive versions of the same system. A model-driven approach can thus reduce the cost of development. It can also reduce the cost of verification: if the transformations are shown or assumed to be correct, each new system or version can be verified in terms of its model, rather than its implementation. This paper introduces an approach to modeldriven engineering that is particularly suited to the development of critical information systems. The language of the models, and the language of the transformations, are amenable to formal analysis. The transformation strategy, and the associated development methodology, are designed to preserve systems integrity and availability. then the dependency upon other processes is reduced; expensive, manual effort can be focused upon surrounding issues of management and validation.
Many approaches to software specification and design make use of invariants: constraints whose tr... more Many approaches to software specification and design make use of invariants: constraints whose truth is preserved under operations on a system or component. Object modelling involves the definition of association invariants: constraints upon the sets of links corresponding to particular associations, most often concerning type, multiplicity, or symmetry. This paper shows how the definitions of operations may be extended to take account of association invariants, so that they may be properly considered when the operations are implemented. It introduces a formal, object-based modelling notation in which the process of extension and implementation, and thus the maintenance of association invariants, can be automated, making it easier to produce correct implementations of an object-oriented design.
Abstract This paper reports upon ten years of experience in the development and application of mo... more Abstract This paper reports upon ten years of experience in the development and application of model-driven technology. The technology in question was inspired by work on formal methods: in particular, by the B toolkit. It was used in the development of a number of information systems, all of which were successfully deployed in real world situations.
Electronic Notes in Theoretical Computer Science, 2008
This paper shows how a domain-specific semantics for object models can be used to support the dev... more This paper shows how a domain-specific semantics for object models can be used to support the development of transformations that reflect a particular implementation strategy. The semantics captures model constraints and domain assumptions in terms of abstract data types, and a transformation is correct if and only if it corresponds to a data refinement. The transformations represent development steps, involving the completion of method descriptions, and validity checks, addressing issues of definedness and consistency. The paper shows how compositions of transformations may be used for the automatic generation of working systems from formal, object-oriented designs.
Electronic Notes in Theoretical Computer Science, 2007
This paper explains precisely how a declarative method language, based upon the formal notations ... more This paper explains precisely how a declarative method language, based upon the formal notations of Z and B, can be used as a basis for automatic code generation. The language is used to describe the intended effect of operations, or methods, upon the components of an object model; each method is defined by a pair of predicates-pre-and post-conditions. Following the automatic incorporation of model invariants, including those arising from class associations, these predicates are extended-again, automatically-to address issues of consistency, definition, and dependency, before being transformed into imperative programs. The result is a formal method for transforming object models into complete, working systems.
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Papers by James Welch