Reasoning about processes in applications such as manufacturing, web services, enterprise modeling, and planning requires the representation of composite processes with complicated flows of control. Previous research in process representation has used formalisms such as Event Systems, Petri nets, and the Unified Modeling Language activity diagrams. The computational hardness of temporal projection problems in Event Systems has been extensively examined in the literature, whereas Petri nets and UML activity diagrams are applied to describe more elaborate processes. This thesis takes a systematic look into the temporal reasoning problems in Event Systems and assigns accurate semantics to both Petri nets and, for the first time, to UML activity diagrams. We give an analysis of computational complexity in temporal projection problems by exploring the boundary between their tractable and intractable subproblems. Our results provide new insights into the prominent role the properties of partial ordering play, however we also show that partial ordering is not the sole source of the intractability as has been claimed in an earlier work by Nebel and B{\"a}ckstr{\"o}m. Two influential modeling languages, Petri nets and UML activity diagrams, are axiomatized as two Basic Action Theories of Situation Calculus. They are called, respectively, SCOPE (Situation Calculus Ontology of PEtri nets) and SCAD (Situation Calculus theory of Activity Diagrams). We provide a Prolog implementation of SCOPE and prove the correctness of this program for regressable queries. We use SCAD to axiomatize the structural and dynamic properties of UML activity diagrams and also provide the first set of computational results with regard to the reachability problems in activity diagrams. The correctness of each of these two axiomatizations is also demonstrated by proving that the theory is satisfiable, and the intended interpretation corresponds to a model of the theory.

Reasoning about processes in applications such as manufacturing, web services, enterprise modeling, and planning requires the representation of composite processes with complicated flows of control. Previous research in process representation has used formalisms such as Event Systems, Petri nets, and the Unified Modeling Language activity diagrams. The computational hardness of temporal projection problems in Event Systems has been extensively examined in the literature, whereas Petri nets and UML activity diagrams are applied to describe more elaborate processes. This thesis takes a systematic look into the temporal reasoning problems in Event Systems and assigns accurate semantics to both Petri nets and, for the first time, to UML activity diagrams. We give an analysis of computational complexity in temporal projection problems by exploring the boundary between their tractable and intractable subproblems. Our results provide new insights into the prominent role the properties of partial ordering play, however we also show that partial ordering is not the sole source of the intractability as has been claimed in an earlier work by Nebel and B{\"a}ckstr{\"o}m. Two influential modeling languages, Petri nets and UML activity diagrams, are axiomatized as two Basic Action Theories of Situation Calculus. They are called, respectively, SCOPE (Situation Calculus Ontology of PEtri nets) and SCAD (Situation Calculus theory of Activity Diagrams). We provide a Prolog implementation of SCOPE and prove the correctness of this program for regressable queries. We use SCAD to axiomatize the structural and dynamic properties of UML activity diagrams and also provide the first set of computational results with regard to the reachability problems in activity diagrams. The correctness of each of these two axiomatizations is also demonstrated by proving that the theory is satisfiable, and the intended interpretation corresponds to a model of the theory.

This thesis sets out a theoretical premise for design research into the space of the designer, working inside the design system or context. The designer is understood as actor, as active agency looking inwards in a comprehensive way to examine where ideas are located and then, how these new insights or perspective might be meaningfully introduced. In order to develop this research, personal journal writing is employed as to develop an understanding about how the designer/actor can actively engage with being at once participant, and observer, of their own design practice. A series of design case studies are carried out, where the role of the designer as actor is critically examined through forms of personal journal writing. What this entails is the establishment of a form of autopoetic system for writing in several voices of the self, and self-as-other working in, and through as design project case studies. I critically evaluate these journal case studies to inform my understanding about the design of dialogic visual communication, where multiple perspectives of self, and self-as-other may be interwoven into the visual design artifact. As a result of conducting this research, I propose the existence of what I term the 'conversational self' as a means for developing new knowledge and knowing through conversational story-telling as design research. My research introduces the 'conversational self' as a generalisable theory for design research which addresses the ways in which the designer might effectively engage with the workings of personal tools and patterns of practice, thus building greater objectivity through recognition of local contexts, and the role of the designer as actor and as a situated self within the design process. My research findings describe a space for the 'conversational self' as the coming together of three linked knowledge systems for creation and learning. I describe this theory as 'agency-centred' design for research about design and experiential knowledge contexts through research into the development of project case studies where individual styles and approaches to learning and thinking which are recognised and valued as implicit tools of and for design practice. Firstly, the conversational journal writing format which I develop situates the designer/ researcher as both participant and observer within their design decision-making. As a result of the uses of the journal format as a practice-based research methodology through case studies, I observe the effect of producing what I term an 'autopoetic' (Maturana and Varela) self-producing system, which enables me to introduce both rational and intuitive content that works in my journal through a range of thinking styles and journal forms. My research strategy involves the writing of several concurrent and interacting levels of internal conversation across 'I', 'You', 'Me' and 'We' as parallel and interactive experiential voices of self through uses of a journal format where a range of experiences are documented as design project narratives. The conversational contexts which this approach offers provide a means for introducing multiple perspectives from self, and selfas- other (as designer, author, subject, agent, person) to explore topics and social knowledge themes through a range of creative conversational learning contexts (Pask, Glanville). In the course of developing this approach I draw on theories about personal constructs (Kelly, Thomas and Harri-Augustein); the self as forms as agency (Archer); about experiential learning and knowledge creation through learning conversations (Baker, Jensen and Kolb) ; and social knowledge as networks, flows and exchange processes (Boisot). Secondly, as a finding from my usage of this journal format, I propose the workings of what I describe as my 'unity of self' system construct as an enabling and generative system for working with social knowledge and the 'self' as forms of agency through internal conversations. Margaret Archer's theory describes the social self as forms of causal agency active in everyday social and experiential contexts. In my case studies I trace the internal dynamics and interactions of 'voices' of self in the journal text, which I evaluate as the workings of conversational levels and layers which engage with a range of details and perspectives for each project using written and non-verbal forms. The design case study projects each describes a particular context for design practice; including institutional, corporate, experimental, and personal design projects. In using this methodology for journal writing, I show how I am able to explore the social interplays of personal/public and individual/collective frameworks for design practice contexts. Thirdly, through my evaluations of the design project case study journals, I observe the emergence of topics and themes in each project around my understanding of the role of context for defining the social and experiential 'materials' (Schon) of the situation. The topics noted from conversations in design case inform what I term my 'contextual field' as the third learning system in my findings from this research. This 'contextual field' is a kind of topical map which provides signposts for working with social and experiential contexts, to design 'ecological narratives' (Krippendorff) as forms of language which are crafted as intentional and strategic design approaches, as responses to the research process of internal reflection about the materials of the situation (Schon) Through usage with my journal format, and unity of self construct, my contextual field topical map provides a framework for developing topics and themes for internal conversations to inform my design production in both 'service' and 'hand' craft project contexts. What results are rich use case studies documented as forms of conversational story-telling where new knowledge emerges as questions and possibilities around the design of visual artifacts and service contexts.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references and index.

Thesis (M.S.)--University of Michigan, 1982.

Thesis (Ph. D.)--University of Sydney, 1992. / Includes tables. Bibliography: leaves 401-409. Also available in print form.

Thesis (M.S.)--University of Michigan, 2005. / Degree information supplied by cataloger. Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1954.

Thesis (M.S.)--University of Michigan, 1951.

Thesis (M.S.)--University of Michigan, 1982.