A realizability semantics for inductive formal topologies, Church's Thesis and Axiom of Choice

We present a Kleene realizability semantics for the intensional level of the Minimalist Foundation, for short mtt, extended with inductively generated formal topologies, Church's thesis and axiom of choice. This semantics is an extension of the one used to show consistency of the intensional level of the Minimalist Foundation with the axiom of choice and formal Church's thesis in previous work. A main novelty here is that such a semantics is formalized in a constructive theory represented by Aczel's constructive set theory CZF extended with the regular extension axiom

A realizability semantics for inductive formal topologies, church’s thesis and axiom of choice

We present a Kleene realizability semantics for the intensional level of the Minimalist Foundation, for short mtt, extended with inductively generated formal topologies, Church's thesis and axiom of choice. This semantics is an extension of the one used to show consistency of the intensional level of the Minimalist Foundation with the axiom of choice and formal Church's thesis in previous work. A main novelty here is that such a semantics is formalized in a constructive theory represented by Aczel's constructive set theory CZF extended with the regular extension axiom

Inductive and Coinductive Topological Generation with Church's thesis and the Axiom of Choice

Here we consider an extension MFcind of the Minimalist Foundation MF for predicative constructive mathematics with the addition of inductive and coinductive definitions sufficient to generate Sambin's Positive topologies, i.e. Martin-L\"of-Sambin formal topologies equipped with a Positivity relation (used to describe pointfree formal closed subsets). In particular the intensional level of MFcind, called mTTcind, is defined by extending with coinductive definitions another theory mTTind extending the intensional level mTT of MF with the sole addition of inductive definitions. In previous work we have shown that mTTind is consistent with Formal Church's Thesis CT and the Axiom of Choice AC via an interpretation in Aczel's CZF+REA. Our aim is to show the expectation that the addition of coinductive definitions to mTTind does not increase its consistency strength by reducing the consistency of mTTcind+CT+AC to the consistency of CZF+REA through various interpretations. We actually reach our goal in two ways. One way consists in first interpreting mTTcind+CT+AC in the theory extending CZF with the Union Regular Extension Axiom, REA_U, a strengthening of REA, and the Axiom of Relativized Dependent Choice, RDC. The theory CZF+REA_U+RDC is then interpreted in MLS*, a version of Martin-L\"of's type theory with Palmgren's superuniverse S. A last step consists in interpreting MLS* back into CZF+REA. The alternative way consists in first interpreting mTTcind+AC+CT directly in a version of Martin-L\"of's type theory with Palmgren's superuniverse extended with CT, which is then interpreted back to CZF+REA. A key benefit of the first way is that the theory CZF+REA_U+RDC also supports the intended set-theoretic interpretation of the extensional level of MFcind. Finally, all the theories considered, except mTTcind+AC+CT, are shown to be of the same proof-theoretic strength.Comment: arXiv admin note: text overlap with arXiv:1905.1196

Inductive and Coinductive Topological Generation with Church's thesis and the Axiom of Choice

In this work we consider an extension MFcind of the Minimalist Foundation MF for predicative constructive mathematics with the addition of inductive and coinductive definitions sufficient to generate Sambin's Positive topologies, namely Martin-Löf-Sambin formal topologies equipped with a Positivity relation (used to describe pointfree formal closed subsets). In particular the intensional level of MFcind, called mTTcind, is defined by extending with coinductive definitions another theory mTTind extending the intensional level mTT of MF with the sole addition of inductive definitions. In previous work we have shown that mTTind is consistent with Formal Church's Thesis CT and the Axiom of Choice AC via an interpretation in Aczel's CZF+REA. Our aim is to show the expectation that the addition of coinductive definitions to mTTind does not increase its consistency strength by reducing the consistency of mTTcind+CT+AC to the consistency of CZF+REA through various interpretations. We actually reach our goal in two ways. One way consists in first interpreting mTTcind+CT+AC in the theory extending CZF with the Union Regular Extension Axiom, REA_U, a strengthening of REA, and the Axiom of Relativized Dependent Choice, RDC. The theory CZF+REA_U+RDC is then interpreted in MLS*, a version of Martin-Löf's type theory with Palmgren's superuniverse S. A last step consists in interpreting MLS* back into CZF+REA. The alternative way consists in first interpreting mTTcind+AC+CT directly in a version of Martin-Löf's type theory with Palmgren's superuniverse extended with CT, which is then interpreted back to CZF+REA. A key benefit of the first way is that the theory CZF+REA_U+RDC also supports the intended set-theoretic interpretation of the extensional level of MFcind. Finally, all the theories considered, except mTTcind+AC+CT, are shown to be of the same proof-theoretic strength

A realizability semantics for inductive formal topologies, Church's Thesis and Axiom of Choice

We present a Kleene realizability semantics for the intensional level of the Minimalist Foundation, for short mTT, extended with inductively generated formal topologies, the formal Church's thesis and axiom of choice. This semantics is an extension of the one used to show the consistency of the intensional level of the Minimalist Foundation with the axiom of choice and the formal Church's thesis in the work by Ishihara, Maietti, Maschio, Streicher [Arch.Math.Logic,57(7-8):873-888,2018]. A main novelty here is that such a semantics is formalized in a constructive theory as Aczel's constructive set theory CZF extended with the regular extension axio

Metaontological Studies relating to the Problem of Universals

My dissertation deals with metaontology or metametaphysics. This is the subdiscipline of philosophy that is concerned with the investigation of metaphysical concepts, statements, theories and problems on the metalevel. It analyses the meaning of metaphysical statements and theories and discusses how they are to be justified. The name "metaontology" is recently coined, but the task of metaontology is the same as Immanuel Kant already dealt with in his Critique of Pure Reason. As methods I use both historical research and logical (or rather semantical) analysis. In order to understand clearly what metaphysical terms or theories mean or should mean we must both look at how they have been characterized in the course of the history of philosophy and then analyse the meanings that have historically been given to them with the methods of modern formal semantics. Metaontological research would be worthless if it could not in the end be applied to solving some substantive ontological questions. In the end of my dissertation, therefore, I give arguments for a solution to the substantively ontological problem of universals, a form of realism about universals called promiscuous realism. To prepare the way for that argument, I argue that the metaontological considerations most relevant to the problem of universals are considerations concerning ontological commitment, as the American philosophers Quine and van Inwagen have argued, not those concerning truthmakers as such philosophers as the Australian realist D. M. Armstrong have argued or those concerning verification conditions as such philosophers as Michael Dummett have argued. To justify this conclusion, I go first through well-known objections to verificationism, and show that they apply also to current verificationist theories such as Dummett's theory and Field's deflationist theory of truth. In the process I also respond to opponents of metaphysics who try to show with the aid of verificationism or structuralism that metaphysical questions would be meaningless or illegitimate in some other way. Having justified the central role of ontological commitment, I try to develop a detailed theory of it. The core of my work is a rigorous formal development of a theory of ontological commitment. I construct it by combining Alonzo Church's theory of ontological commitment with Tarski's theory of truth.Väitöskirjani käsittelee metaontologiaa eli metametafysiikkaa. Tämä on se metafilosofian osa-alue, joka tutkii metafyysisten väitteiden ja termien merkitystä ja sitä, miten metafyysiset väitteet ja teoriat voitaisiin oikeuttaa. Metafysiikka tai ontologia on taas tiede, joka tutkii olevaa yleensä tai kaikkeutta kokonaisuutena. Menetelminä käytän sekä historiallista tutkimusta että loogista (tai pikemminkin semanttista) analyysiä. On olemassa kolme pääasiallista teoriaa siitä, mikä on metaontologian keskeisin käsite. Sellaiset filosofit kuin australialainen Armstrong ovat väittäneet, että se on totuustekijöiden (truthmakers) käsite. Sellaiset anti-realistiset filosofit kuin englantilainen filosofi Michael Dummett ovat taas väittäneet että se on todennettavuusehtojen (verification conditions) käsite. Argumentoin näitä kahta käsitystä vastaan ja kolmannen puolesta, jonka mukaan keskeisin käsite on ontologisten sitoumusten käsite, kuten amerikkalainen filosofi Quine on väittänyt. Argumentoin, että Quinen ontologisten sitoumusten teoria voidaan erottaa hänen muista ontologisista näkemyksistään, kuten hänen semanttisesta holismistaan, ontologisesta relativismistaan tai strukturalismistaan, mitkä ovat mielestäni virheellisiä. Väitöskirjani ydin on täsmällinen teoria ontologisista sitoumuksista, jonka rakennan yhdistämällä Alonzo Churchin teoriaa ontologisista sitoumuksista Alfred Tarskin totuusteoriaan. Metaontologinen tutkimus olisi arvotonta, ellei sitä voisi lopulta käyttää substantiivisten ontologisten kysymysten ratkaisemiseen. Käsittelen siksi väitöskirjani loppupuolella yhtä perinteistä ontologian ongelmaa, universaalien ongelmaa. Jo Aristoteles määritteli teoksessaan Tulkinnasta universaalien olevan olioita, jotka (Lauri Carlsonin käännöksen mukaan) luonnostaan predikoidaan (sanotaan) monesta. Universaaliongelma koskee sitä, ovatko tällaiset universaalit vain kielellisiä ilmauksia, kuten yleisnimet, verbit ja adjektiivit, tai ihmismielestä riippuvia olioita, kuten yleiskäsitteet, vai voidaanko myös sanoa, että maailmassa itsessään olevia olioita voidaan predikoida jostakin. Realistin mukaan vastaus on myöntävä. Esitän väitöskirjan lopussa alustavan argumentin universaaleja koskevan realismin puolesta

LFTOP: An LF based approach to domain specific reasoning

Specialized vocabulary, notations and inference rules tailored for the description, analysis and reasoning of a domain is very important for the domain. For domain-specific issues researchers focus mainly on the design and implementation of domain-specific languages (DSL) and pay little attention to the reasoning aspects. We believe that domain-specific reasoning is very important to help the proofs of some properties of the domains and should be more concise, more reusable and more believable. It deserves to be investigated in an engineering way. Type theory provides good support for generic reasoning and verification. Many type theorists want to extend uses of type theory to more domains, and believe that the methods, ideas, and technology of type theory can have a beneficial effect for computer assisted reasoning in many domains. Proof assistants based on type theory are well known as effective tools to support reasoning. But these proof assistants have focused primarily on generic notations for representation of problems and are oriented towards helping expert type theorists build proofs efficiently. They are successful in this goal, but they are less suitable for use by non-specialists. In other words, one of the big barriers to limit the use of type theory and proof assistant in domain-specific areas is that it requires significant expertise to use it effectively. We present LFTOP ― a new approach to domain-specific reasoning that is based on a type-theoretic logical framework (LP) but does not require the user to be an expert in type theory. In this approach, users work on a domain-specific interface that is familiar to them. The interface presents a reasoning system of the domain through a user-oriented syntax. A middle layer provides translation between the user syntax and LF， and allows additional support for reasoning (e.g. model checking). Thus, the complexity of the logical framework is hidden but we also retain the benefits of using type theory and its related tools, such as precision and machine-checkable proofs. The approach is being investigated through a number of case studies. In each case study, the relevant domain-specific specification languages and logic are formalized in Plastic. The relevant reasoning system is designed and customized for the users of the corresponding specific domain. The corresponding lemmas are proved in Plastic. We analyze the advantages and shortcomings of this approach, define some new concepts related to the approach, especially discuss issues arising from the translation between the different levels. A prototype implementation is developed. We illustrate the approach through many concrete examples in the prototype implementation. The study of this thesis shows that the approach is feasible and promising, the relevant methods and technologies are useful and effective

The appeal to immediacy of the Erfahrungshunger decades : a socio-historical clarification and diagnosis

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal