Unifying Theories of Logics with Undefinedness

A relational approach to the question of how different logics relate formally is described. We consider three three-valued logics, as well as classical and semi-classical logic. A fundamental representation of three-valued predicates is developed in the Unifying Theories of Programming (UTP) framework of Hoare and He. On this foundation, the five logics are encoded semantically as UTP theories. Several fundamental relationships are revealed using theory linking mechanisms, which corroborate results found in the literature, and which have direct applicability to the sound mixing of logics in order to prove facts. The initial development of the fundamental three-valued predicate model, on which the theories are based, is then applied to the novel systems-of-systems specification language CML, in order to reveal proof obligations which bridge a gap that exists between the semantics of CML and the existing semantics of one of its sub-languages, VDM. Finally, a detailed account is given of an envisioned model theory for our proposed structuring, which aims to lift the sentences of the five logics encoded to the second order, allowing them to range over elements of existing UTP theories of computation, such as designs and CSP processes. We explain how this would form a complete treatment of logic interplay that is expressed entirely inside UTP

Relations between logic and mathematics in the work of Benjamin and Charles S. Peirce.

Charles Peirce (1839-1914) was one of the most important logicians of the nineteenth century. This thesis traces the development of his algebraic logic from his early papers, with especial attention paid to the mathematical aspects. There are three main sources to consider. 1) Benjamin Peirce (1809-1880), Charles's father and also a leading American mathematician of his day, was an inspiration. His memoir Linear Associative Algebra (1870) is summarised and for the first time the algebraic structures behind its 169 algebras are analysed in depth. 2) Peirce's early papers on algebraic logic from the late 1860s were largely an attempt to expand and adapt George Boole's calculus, using a part/whole theory of classes and algebraic analogies concerning symbols, operations and equations to produce a method of deducing consequences from premises. 3) One of Peirce's main achievements was his work on the theory of relations, following in the pioneering footsteps of Augustus De Morgan. By linking the theory of relations to his post-Boolean algebraic logic, he solved many of the limitations that beset Boole's calculus. Peirce's seminal paper `Description of a Notation for the Logic of Relatives' (1870) is analysed in detail, with a new interpretation suggested for his mysterious process of logical differentiation. Charles Peirce's later work up to the mid 1880s is then surveyed, both for its extended algebraic character and for its novel theory of quantification. The contributions of two of his students at the Johns Hopkins University, Oscar Mitchell and Christine Ladd-Franklin are traced, specifically with an analysis of their problem solving methods. The work of Peirce's successor Ernst Schröder is also reviewed, contrasting the differences and similarities between their logics. During the 1890s and later, Charles Peirce turned to a diagrammatic representation and extension of his algebraic logic. The basic concepts of this topological twist are introduced. Although Peirce's work in logic has been studied by previous scholars, this thesis stresses to a new extent the mathematical aspects of his logic - in particular the algebraic background and methods, not only of Peirce but also of several of his contemporaries

Topological data analysis and geometry in quantum field dynamics

Many non-perturbative phenomena in quantum field theories are driven or accompanied by non-local excitations, whose dynamical effects can be intricate but difficult to study. Amongst others, this includes diverse phases of matter, anomalous chiral behavior, and non-equilibrium phenomena such as non-thermal fixed points and thermalization. Topological data analysis can provide non-local order parameters sensitive to numerous such collective effects, giving access to the topology of a hierarchy of complexes constructed from given data. This dissertation contributes to the study of topological data analysis and geometry in quantum field dynamics. A first part is devoted to far-from-equilibrium time evolutions and the thermalization of quantum many-body systems. We discuss the observation of dynamical condensation and thermalization of an easy-plane ferromagnet in a spinor Bose gas, which goes along with the build-up of long-range order and superfluidity. In real-time simulations of an over-occupied gluonic plasma we show that observables based on persistent homology provide versatile probes for universal dynamics off equilibrium. Related mathematical effects such as a packing relation between the occurring persistent homology scaling exponents are proven in a probabilistic setting. In a second part, non-Abelian features of gauge theories are studied via topological data analysis and geometry. The structure of confining and deconfining phases in non-Abelian lattice gauge theory is investigated using persistent homology, which allows for a comprehensive picture of confinement. More fundamentally, four-dimensional space-time geometries are considered within real projective geometry, to which canonical quantum field theory constructions can be extended. This leads to a derivation of much of the particle content of the Standard Model. The works discussed in this dissertation provide a step towards a geometric understanding of non-perturbative phenomena in quantum field theories, and showcase the promising versatility of topological data analysis for statistical and quantum physics studies

Understanding and evolving the Rust programming language

Rust is a young systems programming language that aims to fill the gap between high-level languages—which provide strong static guarantees like memory and thread safety—and low-level languages—which give the programmer fine-grained control over data layout and memory management. This dissertation presents two projects establishing the first formal foundations for Rust, enabling us to better understand and evolve this important language: RustBelt and Stacked Borrows. RustBelt is a formal model of Rust’s type system, together with a soundness proof establishing memory and thread safety. The model is designed to verify the safety of a number of intricate APIs from the Rust standard library, despite the fact that the implementations of these APIs use unsafe language features. Stacked Borrows is a proposed extension of the Rust specification, which enables the compiler to use the strong aliasing information in Rust’s types to better analyze and optimize the code it is compiling. The adequacy of this specification is evaluated not only formally, but also by running real Rust code in an instrumented version of Rust’s Miri interpreter that implements the Stacked Borrows semantics. RustBelt is built on top of Iris, a language-agnostic framework, implemented in the Coq proof assistant, for building higher-order concurrent separation logics. This dissertation begins by giving an introduction to Iris, and explaining how Iris enables the derivation of complex high-level reasoning principles from a few simple ingredients. In RustBelt, this technique is exploited crucially to introduce the lifetime logic, which provides a novel separation-logic account of borrowing, a key distinguishing feature of the Rust type system.Rust ist eine junge systemnahe Programmiersprache, die es sich zum Ziel gesetzt hat, die Lücke zu schließen zwischen Sprachen mit hohem Abstraktionsniveau, die vor Speicher- und Nebenläufigkeitsfehlern schützen, und Sprachen mit niedrigem Abstraktionsniveau, welche dem Programmierer detaillierte Kontrolle über die Repräsentation von Daten und die Verwaltung des Speichers ermöglichen. Diese Dissertation stellt zwei Projekte vor, welche die ersten formalen Grundlagen für Rust zum Zwecke des besseren Verständnisses und der weiteren Entwicklung dieser wichtigen Sprache legen: RustBelt und Stacked Borrows. RustBelt ist ein formales Modell des Typsystems von Rust einschließlich eines Korrektheitsbeweises, welcher die Sicherheit von Speicherzugriffen und Nebenläufigkeit zeigt. Das Modell ist darauf ausgerichtet, einige komplexe Komponenten der Standardbibliothek von Rust zu verifizieren, obwohl die Implementierung dieser Komponenten unsichere Sprachkonstrukte verwendet. Stacked Borrows ist eine Erweiterung der Spezifikation von Rust, die es dem Compiler ermöglicht, den Quelltext mit Hilfe der im Typsystem kodierten Alias-Informationen besser zu analysieren und zu optimieren. Die Tauglichkeit dieser Spezifikation wird nicht nur formal belegt, sondern auch an echten Programmen getestet, und zwar mit Hilfe einer um Stacked Borrows erweiterten Version des Interpreters Miri. RustBelt basiert auf Iris, welches die Konstruktion von Separationslogiken für beliebige Programmiersprachen im Beweisassistenten Coq ermöglicht. Diese Dissertation beginnt mit einer Einführung in Iris und erklärt, wie komplexe Beweismethoden mit Hilfe weniger einfacher Bausteine hergeleitet werden können. In RustBelt wird diese Technik für die Umsetzung der „Lebenszeitlogik“ verwendet, einer Erweiterung der Separationslogik mit dem Konzept von „Leihgaben“ (borrows), welche eine wichtige Rolle im Typsystem von Rust spielen.This research was supported in part by a European Research Council (ERC) Consolidator Grant for the project "RustBelt", funded under the European Union’s Horizon 2020 Framework Programme (grant agreement no. 683289)

Report of the Governor of Idaho, 1889

Annual Message to Congress with Documents: Pres. Harrison. 3 Dec. HED 1, 51-1, v1-18, 15546p. [2714-2733] Division and reduction of the Sioux reservation in Dakota: the opening of portions of Indian Territory for settlement; no policy for the establishment of Indian reservations in Alaska: annual report of the Sec.of War (Serials 2715-2720); annual report of the Sec. of Interior (Serials 2724-2730); annual report of the Gen. Land Office (Serial 2724); annual report of the CIA (Serial 2725); etc

Donaldson–Thomas invariants of threefold flops

This thesis is about a class of complex algebraic threefolds known as flops, which are an important part of the Minimal Model Program in birational geometry. Threefold flops are commonly studied via their enumerative invariants, and here we focus on one such type of invariant: refined Donaldson–Thomas invariants. We develop theoretical aspects of refined Donaldson–Thomas theory for threefold flops, which allow us to understand their stability conditions and cyclic A∞-deformation theory. With these new methods, we are able to sidestep common computational barriers in the field and fully determine the Donaldson–Thomas invariants for an infinite family of flops, which includes many new examples. Our results show that a refined version of the strong-rationality conjecture of Pandharipande–Thomas holds in this setting, and also that refined Donaldson–Thomas invariants are not sufficiently fine to determine flops. Where possible we work motivically, computing invariants in the Grothendieck ring of varieties, but we also produce Hodge theoretic realisations of the invariants

W*-Bundles

This thesis collates, extends and applies the abstract theory of W*-bundles. Highlights include the standard form for W*-bundles, a bicommutant theorem for W*-bundles, and an investigation of completions, ideals, and quotients of W*-bundles. The Triviality Problem, whether all W*-bundles with fibres isomorphic to the hyperfinite II_1 factor are trivial, is central to this thesis. Ozawa's Triviality Theorem is presented, and property gamma and the McDuff property for W*-bundles are investigated thoroughly. Ozawa's Triviality Theorem is applied to some new examples such as the strict closures of Villadsen algebras and non-trivial C(X)-algebras. The solution to the Triviality Problem in the locally trivial case, obtained by myself and Pennig, is included. A theory of sub-W*-bundles is developed along the lines of Jones' subfactor theory. A sub-W*-bundle encapsulates a tracially continuous family of subfactors in a single object. The basic construction and the Jones tower are generalised to this new setting and the first examples of sub-W*-bundles are constructed