Aspects of the constructive omega rule within automated deduction

In general, cut elimination holds for arithmetical systems with the w -rule, but not for systems with ordinary induction. Hence in the latter, there is the problem of generalisation, since arbitrary formulae can be cut in. This makes automatic theorem -proving very difficult. An important technique for investigating derivability in formal systems of arithmetic has been to embed such systems into semi- formal systems with the w -rule. This thesis describes the implementation of such a system. Moreover, an important application is presented in the form of a new method of generalisation by means of "guiding proofs" in the stronger system, which sometimes succeeds in producing proofs in the original system when other methods fail

Aristotelian Potential Infinity

Online philosophy seminar notes, for virtual conference on the Aristotelian philosophy of mathematics, hosted by University of Geneva (organiser Ryan Miller), June 15, 202

The theory of inconsistency: inconsistant mathematics and paraconsistent logic

Each volume includes author's previously published papers.Bibliography: leaves 147-151 (v. 1).3 v. :Thesis (D.Sc.)--University of Adelaide, School of Mathematical Sciences, 200

Leaving mathematics as it is: Wittgenstein’s later philosophy of mathematics

Wittgenstein’s later philosophy of mathematics has been widely interpreted to involve Wittgenstein’s making dogmatic requirements of what can and cannot be mathematics, as well as involving Wittgenstein dismissing whole areas (e.g. set theory) as not legitimate mathematics. Given that Wittgenstein promised to ‘leave mathematics as it is’, Wittgenstein is left looking either hypocritical or confused. This thesis will argue that Wittgenstein can be read as true to his promise to ‘leave mathematics as it is’ and that Wittgenstein can be seen to present coherent, careful and non-dogmatic treatments of philosophical problems in relation to mathematics. If Wittgenstein’s conception of philosophy is understood in sufficient detail, then it is possible to lift the appearance of confusion and contradiction in his work on mathematics. Whilst apparently dogmatic and sweeping claims figure in Wittgenstein’s writing, they figure only as pictures to be compared against language-use and not as definitive accounts (which would claim exclusive right to correctness). Wittgenstein emphasises the importance of the applications of mathematics and he feels that our inclination to overlook the connections of mathematics with its applications is a key source of a number of philosophical problems in relation to mathematics. Wittgenstein does not emphasise applications to the exclusion of all else or insist that nothing is mathematics unless it has direct applications. Wittgenstein does question the alleged importance of certain non-applied mathematical systems such as set theory and the logicist systems of Frege and Russell. But his criticism is confined to the aspirations towards philosophical insight that has been attributed to those systems. This is consonant with Wittgenstein’s promises in (PI, §124) to ‘leave mathematics as it is’ and to see ‘leading problems of mathematical logic’ as ‘mathematical problems like any other.’ It is the aim of this thesis to see precisely what Wittgenstein means by these promises and how he goes about keeping them

Some Transfinite Generalisations of Gödel's Incompleteness Theorem

International audienceGodel's incompleteness theorem can be seen as a limitation result of usual computing theory: it does not exist a ( nite) software that takes as input a rst order formula on the integers and decides (after a nite number of computations and always with a right answer) whether this formula is true or false. There are also many other limitations of usual computing theory that can be seen as generalisations of Godel incompleteness theorem: for example the halting problem, Rice theorem, etc. In this paper, we will study what happens when we consider more powerful computing devices: these \trans nite devices" will be able to perform classical computations and to use bits of memory, where is a xed in nite cardinal. For example, = @0 (the countable cardinal, i.e. the cardinal of N), or = C(the cardinal of R). We will see that for these \trans nite devices" almost all Godel's limitations results have relatively simple generalisations

Naturalising Badiou: mathematical ontology and structural realism

This thesis offers a naturalist revision of Alain Badiou’s philosophy. This goal is pursued through an encounter of Badiou’s mathematical ontology and theory of truth with contemporary trends in philosophy of mathematics (mathematical structuralism) and philosophy of science (ontic structural realism). I take issue with Badiou’s inability to elucidate the link between the empirical and the ontological, and his residual reliance on a Heideggerian project of fundamental ontology, which undermines his own immanentist principles. I will argue for both a bottom-up naturalisation of Badiou’s philosophical approach to mathematics (insisting on an account mindful of the socio-biological roots of our mathematical abilities and concepts – brains to universe) and a top-down naturalisation (arguing that our best physical theories seem to indicate a collapse of the distinction between the mathematical and the non-mathematical – universe to brains). Articulating my particular understanding of what realism and naturalism should commit us to, I propose a creative fusion of Badiou’s attention to metamathematical results with a structural-informational metaphysics, proposing a ‘matherialism’ uniting the more daring speculative insights of the former with the naturalist and empiricist commitments motivating the latter