title: The Algebraic Properties of if-then-else with Commutative Three-Valued Tests

authors: Su, Roger Chi-Wei

subjects: if-then-else

abstract: This thesis studies an algebraic model of computable programs and the if-then-else operation. The programs here are considered deterministic, but not assumed to be always halting, so they are modelled by a semigroup of partial functions, with several extra operations in addition to the original binary operation of the semigroup.
The if-then-else operation involves not only programs, but logical tests too. Hence, it calls for a separate algebra of tests. Evaluating a test often requires running another program, so the tests are also possibly non halting. When tests do not always halt, the results of conjunctions (logical ‘and’) and disjunctions (logical ‘or’) can differ, depending on whether sequential or parallel evaluation is applied. The parallel evaluation is what this thesis adopts.
The overall ‘program algebra’ consists of two sorts, one of programs and the other of tests. Each sort has its own operations, and there are hybrid operations such as if-then-else which involve both sorts. This thesis establishes the axioms of all these operations by building an embedding from the abstract program algebra into a concrete one. At the end is a discussion on the algebra of tests without the programs, where the differences between the two evaluation paradigms are explored in detail.

text: The Algebraic Properties of if-then-else with Commutative Three-Valued Tests This thesis studies an algebraic model of computable programs and the if-then-else operation. The programs here are considered deterministic, but not assumed to be always halting, so they are modelled by a semigroup of partial functions, with several extra operations in addition to the original binary operation of the semigroup.
The if-then-else operation involves not only programs, but logical tests too. Hence, it calls for a separate algebra of tests. Evaluating a test often requires running another program, so the tests are also possibly non halting. When tests do not always halt, the results of conjunctions (logical ‘and’) and disjunctions (logical ‘or’) can differ, depending on whether sequential or parallel evaluation is applied. The parallel evaluation is what this thesis adopts.
The overall ‘program algebra’ consists of two sorts, one of programs and the other of tests. Each sort has its own operations, and there are hybrid operations such as if-then-else which involve both sorts. This thesis establishes the axioms of all these operations by building an embedding from the abstract program algebra into a concrete one. At the end is a discussion on the algebra of tests without the programs, where the differences between the two evaluation paradigms are explored in detail.

year: 2018

title: Ontologies on the semantic web

authors: Legg, Catherine

subjects: World Wide Web

abstract: As an informational technology, the World Wide Web has enjoyed spectacular success. In just ten years it has transformed the way information is produced, stored, and shared in arenas as diverse as shopping, family photo albums, and high-level academic research. The “Semantic Web” was touted by its developers as equally revolutionary but has not yet achieved anything like the Web’s exponential uptake. This 17 000 word survey article explores why this might be so, from a perspective that bridges both philosophy and IT.

text: Ontologies on the semantic web As an informational technology, the World Wide Web has enjoyed spectacular success. In just ten years it has transformed the way information is produced, stored, and shared in arenas as diverse as shopping, family photo albums, and high-level academic research. The “Semantic Web” was touted by its developers as equally revolutionary but has not yet achieved anything like the Web’s exponential uptake. This 17 000 word survey article explores why this might be so, from a perspective that bridges both philosophy and IT.

year: 2007

title: Replacing medical and social models of disability by a communities-based model of equal access for people of differing abilities: A Māori perspective

authors: Hickey, Huhana

subjects: New Zealand

abstract: I argue here that although the social model of disability which currently prevails in New Zealand is preferable in many ways to the earlier medical model, it is nevertheless based on a largely uni-dimensional concept of society and continues an established tradition of negativity, one that is evident in the ongoing use of the word 'disabled' itself by those who subscribe to the social model. I argue here that the social model of disability should be replaced by a communities-based model of equal access for people of differing abilities, one that is, in the New Zealand context, informed by a further developed Māori model of health and wellbeing proposed by Mason Durie, Te Whare Tapa Whā. This mode is designed in such a way as to accommodate difference and diversity. In the discussion of different models, I use the words 'disabled' and 'disability'; in other contexts, I replace 'disabled people' by 'people of differing abilities'.

text: Replacing medical and social models of disability by a communities-based model of equal access for people of differing abilities: A Māori perspective I argue here that although the social model of disability which currently prevails in New Zealand is preferable in many ways to the earlier medical model, it is nevertheless based on a largely uni-dimensional concept of society and continues an established tradition of negativity, one that is evident in the ongoing use of the word 'disabled' itself by those who subscribe to the social model. I argue here that the social model of disability should be replaced by a communities-based model of equal access for people of differing abilities, one that is, in the New Zealand context, informed by a further developed Māori model of health and wellbeing proposed by Mason Durie, Te Whare Tapa Whā. This mode is designed in such a way as to accommodate difference and diversity. In the discussion of different models, I use the words 'disabled' and 'disability'; in other contexts, I replace 'disabled people' by 'people of differing abilities'.

year: 2006-02