VictorJuiz/thesis huggingface dataset:
Small model theorems for data independent systems in Alloy
Keywords: Automated verification
data independence
Alloy

A system is data independent in a type T if the only operations allowed on variables of type T are input, output, assignment and equality testing. This property can be exploited to give procedures for the automatic verification of such systems independently of the instance of the type T. Alloy is an extension of first-order logic for modelling software systems. Alloy has a fully automatic analyzer which attempts to refute Alloy formulas by searching for counterexamples within a finite scope. However, failure to find a counterexample does not prove the formula correct. A small model theorem is a theorem which shows that if a formula has a model then it has a model within some finite scope. The contribution of this thesis is to give a small model theorem which applies when modelling data-independent systems in Alloy. The theorem allows one to detect automatically whether an Alloy formula is data independent in some type T and then calculate a threshold scope for T, thereby completing the analysis of the automatic analyzer with respect to the type T. We derive the small model theorem using a model-theoretic approach. We build on the standard semantics of the Alloy language and introduce a more abstract interpretation of formulas, by way of a Galois insertion. This more abstract interpretation gives the same truth value as the original interpretation for many formulas. Indeed we show that this property holds for any formula built with a limited set of language constructors which we call data-independent constructors. The more abstract interpretation is designed so that it often lies within a finite scope and we can calculate whether this is the case and exactly how big the finite scope need be from the types of the free variables in the formula. In this way we can show that if a formula has any instance or counterexample at all then it has one within a threshold scope, the size of which we can calculate.
Social evolution and sex allocation theory
Keywords: Natural Selection
Behavioural Ecology
Sociobiology
Sex ratios

The study of sex allocation is one of the most successful areas in evolutionary biology: its theoretical predictions have been supported by experimental, observational and comparative approaches. Here, I develop sex allocation theory as follows: (1) I use fertility insurance theory to predict the sex ratio strategy of the malaria parasite, in response to human medical interventions that increase mortality and decrease fertility of the parasite’s various sexual stages; (2) Haplodiploidy has been suggested as a driver of the evolution of eusociality, as under this genetic system a female may be more related to her sister than to her own offspring. I examine a model considering queen versus worker control over the sex ratio of the colony and show that haplodiploidy alone does not explain the evolution of helping; (3) I follow up this study of the haplodiploidy hypothesis by examining the idea that split-sex ratios may favour the evolution of eusociality in haplodiploid species.
I study the two mechanisms of split sex ratios, that are found in natural populations and may have been important in the transition to eusociality: queen virginity and queen replacement. I focus on the impact of worker reproduction by considering the effect of woker producing a fraction of the colony offspring and by considering variation in the workers’ offspring sex ratio. My analysis shows that worker reproduction does not promote the evolution of helping in haplodiploid species; (4) I examine the evolution and function of a sterile soldier caste in parasitoid wasps from the genus Encyrtidae. Two main functions have been hypothesized for the emergence of soldiers: spiteful mediation of a sex ratio conflict in mixed-sex broods, and altruistic protection and 7 facilitation of the development of relatives.
I develop a model considering variation in the oviposition behaviour of females, that may produce single-sex or mixed-sex broods. I show that, in accordance with previous theory, females are expected to produce more soldiers than males, under the sex ratio conflict hypothesis. I also show that one of the consequences of this costly conflict is that females are favoured to produce single-sex broods over mixed-sex broods.
Topics in portfolio choice: qualitative properties, time consistency and investment under model uncertainty
Keywords: Time Consistency
Model Uncertainty
Portfolio Optimization
Mathematical Finance

The study of expected utility maximization in continuous-time stochastic market models dates back to the seminal work of Merton 1969 and has since been central to the area of Mathematical Finance. The associated stochastic optimization problems have been extensively studied. The problem formulation relies on two strong underlying assumptions: the ability to specify the underpinning market model and the knowledge of the investor's risk preferences. However, neither of these inputs is easily available, if at all. Resulting issues have attracted continuous attention and prompted very active and diverse lines of research. This thesis seeks to contribute towards this literature and questions related to both of the above issues are studied. Specifically, we study the implications of certain qualitative properties of the utility function; we introduce, and study various aspects of, the notion of robust forward investment criteria; and we study the investment problem associated with risk- and ambiguity-averse preference criteria defined in terms of quasiconcave utility functionals.
Split intransitivity in old Japanese
Keywords: unergatives
Japanese
unaccusatives
split intransitivity

According to the Unaccusative Hypothesis (Perlmutter 1978), intransitive verbs fall in two distinct classes: the unaccusatives (whose subjects originate as direct objects) and the unergatives (whose subjects originate as subjects). Although there are studies of split intransitivity in Modern Japanese and European languages, very few exist for earlier stages of Japanese. To fill in part of this gap, this thesis presents a comprehensive investigation of split intransitivity in Old Japanese (largely, 8th century Japanese).
The descriptive and analytic work of this research is based on the newly developed ‘Oxford Corpus of Old Japanese’ (OCOJ). It consists of original and romanized Old Japanese texts, with a wide range of information including the original orthography, part-of-speech, morphology and syntactic constituency in the form of XML tags following TEI conventions. It is part of a larger collaborative research project: ‘Verb semantics and argument realization in pre-modern Japanese: A comprehensive study of the basic syntax of pre-modern Japanese’, in which my DPhil project is situated. As part of my DPhil project, I took part in the analysis and tagging of the OCOJ, in addition to contributing to translation.
My original contribution to knowledge is a comprehensive investigation and in-depth analysis of the lexical-semantic aspects of split intransitivity in relation to its morpho-syntactic expressions in Old Japanese. This includes: exploring to what extent intransitive verbs could be classified as unaccusative and unergative, what factors are involved in the classification, how they interact, what are the possible ways of representation, and the theoretical implications it brings to linguistic theory in general. Syntactically, I looked into manifestations specific to Old Japanese (e.g. perfective auxiliary selection), and also examined to what extent diagnostics – which show split intransitivity in English, Italian and Modern Japanese (e.g. N+V compounding and resultative construction) – could be applied to Old Japanese. Semantically, I investigated various semantic factors and proposed basic and complex models of the interaction between intentionality and affectedness in Old Japanese. I also proposed a ‘complex format for representing simple event structures’ which enhances the understanding of semantic aspects of split intransitivity. As such, the results of my research not only contribute to a detailed understanding of Old Japanese verbs, but also have implications for linguistic theory in general.
Analysing layered security protocols
Keywords: TLS
protocol layering
strand spaces
WebAuth
computer security
security protocols

Many security protocols are built as the composition of an application-layer protocol and a secure transport protocol, such as TLS. There are many approaches to proving the correctness of such protocols. One popular approach is verification by abstraction, in which the correctness of the application-layer protocol is proven under the assumption that the transport layer satisfies certain properties, such as confidentiality. Following this approach, we adapt the strand spaces model in order to analyse application-layer protocols that depend on an underlying secure transport layer, including unilaterally authenticating secure transport protocols, such as unilateral TLS. Further, we develop proof rules that enable us to prove the correctness of application-layer protocols that use either unilateral or bilateral secure transport protocols. We then illustrate these rules by proving the correctness of WebAuth, a single-sign-on protocol that makes extensive use of unilateral TLS.
In this thesis we also present a full proof of the model's soundness. In particular, we prove that, subject to a suitable independence assumption, if there is an attack against the application-layer protocol when layered on top of a particular secure transport protocol, then there is an attack against the abstracted model of the application-layer protocol. In contrast to existing work in this area, the independence assumption consists of eight statically-checkable conditions, meaning that it can be checked statically, rather than having to consider all possible runs of the protocol.
Lastly, we extend the model to allow protocols that consist of an arbitrary number of layers to be proven correct. In this case, we prove the correctness of the intermediate layers using the high-level strand spaces model, by abstracting away from the underlying transport-layers. Further, we extend the above soundness results in order to prove that the multi-layer approach is sound. We illustrate the effectiveness of our technique by proving the correctness of a couple of simple multi-layer protocols.
'And from his side came blood and milk': the martyrdom of St Philotheus of Antioch in Coptic Egypt
Keywords: hagiography
Coptic
cult of saints
martyr

My thesis examines the function and development of the cult of saints in Coptic Egypt. For this purpose I focus primarily on the material provided by the texts forming the Coptic hagiographical tradition of the early Christian martyr Philotheus of Antioch, and more specifically - the Martyrdom of St Philotheus of Antioch (Pierpont Morgan M583). This Martyrdom is a reflection of a once flourishing cult which is attested in Egypt by rich textual and material evidence. This text enjoyed great popularity not only in Egypt, but also in other countries of the Christian East, since his dossier includes texts in Coptic, Georgian, Ethiopic, and Arabic.
This thesis examines the literary and historical background of the Martyrdom of Philotheus and similar hagiographical texts. It also explores the goals and concerns of the authors and editors of Coptic martyr passions and their intended audience. I am arguing that these texts were produced in order to perform multiple functions: to justify and promote the cult of a particular saint, as an educational tool, and as an important structural element of liturgical celebrations in honour of the saint.
Another aim of this work is to stress the entertainment value of such texts. I explore the sources used by Coptic hagiographers for creating such entertaining stories, as well as the methods they used to re-work certain theological concepts and make them more accessible to the audience.
The thesis begins with description of the manuscript tradition of Philotheus and a brief outline and comparison of its main versions. The second chapter discusses the place of the Martyrdom of Philotheus in Coptic hagiography and its connection to the so-called cycles. The next two chapters explore the motifs and topoi characteristic of Coptic martyr passions, especially the legend of Diocletian the Persecutor and the image of Antioch as the Holy City in Coptic hagiography, as these two motifs appear in one way or another in the majority of the martyr passions. Chapter 5 is dedicated to one of the focal points in the Martyrdom - the miracle of resurrection and the tour of hell – and its literary and theological background. Chapter 6 discusses representations of magic and paganism in Coptic hagiography and some of the concerns of Coptic hagiographers. In the last chapter I explore the geography of the cult, its iconographic and hymnographic dimensions and the transformation of the perception of the saint; the second part of this chapter discusses the questions of performance, authorship and audience.
Surface modified polymers to introduce antibacterial activities
Keywords: Surface Modification
Introducing Antibacterial Activities

This thesis is concerned with the chemical surface modification of several commercial industrial polymers in order to introduce antibacterial activity. Surface modification of polymers including LDPE, PE-fibre, MDPE, UHMPE and PS-XAD4 by carbene insertion reaction and diazo coupling was carried out using two diazo systems, urea diaryl diazo system and bis (dimethylamino) diaryl system. Successful surface modification on polymers was achieved while bulk properties of polymers were maintained.
ATR IR and combustion analysis were used to characterize modified polymer. Clear ATR IR absorption peaks and colour change during diazo coupling indicated successful surface modification. Surface coverage of modified polymers was calculated using nitrogen content detected by combustion analysis. Modified polymers binding with several biocidal agents including hydrogen peroxide, bleach and penicillin V were prepared and antibacterial activity was tested against S. aureus and E. coli. Modified polymers using the urea diazo system showed negative bioassay results, while modified polymer using the bis (dimethylamino) diaryl system showed excellent antibacterial activity.
Direct injection gasoline engine particulate emissions
Keywords: engines
gasoline
particulate emissions
direct injection

Direct fuel injection technology is increasingly being applied to the spark ignition internal combustion engine as one of the many actions required to reduce the CO2 emissions from road transport. Whilst the potential for CO2 reductions is compelling, the technology is not without disadvantages. Early examples typically emitted over an order of magnitude more Particulate Matter (PM) than vehicles with conventional spark ignition engines. Consequently, future revisions to European and North American exhaust emissions legislation are likely to regulate the particulate emissions from vehicles with direct injection gasoline engines. This thesis undertakes to investigate a) instrumentation capable of simultaneously resolving the number concentration and size distribution of particles in the 5-1000 nm size range and b) the factors affecting the PM emissions from spark ignition engines with direct fuel injection. The first objective is achieved by evaluation and comparison of a differential mobility spectrometer; photo-acoustic soot sensor; condensation particle counter and electrical low pressure impactor. To address the second question, a differential mobility spectrometer is applied to quantify the PM emissions from a number of direct injection gasoline engines, together with investigation of their dependence on various calibratable parameters, operating temperature and fuel composition. The differential mobility spectrometer showed good agreement with the other more established instruments tested. Moreover, it exhibited a faster time response and finer resolution in particle size. The number weighted size distribution of the PM emitted was typically lognormal with either one or two modes located between 20 and 100 nm. Chemical analysis of PM samples showed the presence of elemental carbon, volatile organic material and sulphates. Transient PM measurements enabled short time-scale events such as mode switching between homogeneous and stratified mixture preparation to be identified. PM number concentrations in stratified mode exceeded those in homogeneous mode by a factor of 10-100. Dynamometer based experiments showed that PM emissions increase for rich air fuel ratios, retarded fuel injection and advanced ignition events. They also demonstrated a strong dependence on fuel composition: the highest PM emissions were measured with an aromatic fuel, whereas blending alcohols such as methanol or ethanol tended to suppress PM emissions, particularly in the accumulation mode size range. These measurements are amongst the first of their kind and demonstrate the applicability of the differential mobility spectrometer to the measurement of ultra-fine particulate emissions from engines with direct fuel injection systems. Numerous explanations are put forward to describe the data obtained, together with suggestions for future work on PM control and abatement.
Numerical analysis of variational problems in atomistic interaction models
Keywords: 65N60
65Z05
65N25

The present thesis consists of two parts. The first part is devoted to the analysis of discretizations of a class of basic electronic density functionals. In the second part we suggest and analyze Quasicontinuum Methods for an atomistic interaction potential that is based on a field.
We begin by formulating and analyzing a model for the study of finite clusters of atoms or localized defects in infinite crystals based on a version of the classical Thomas{Fermi{Dirac{von Weizs?acker density functional. We show that the resulting constrained optimization problem has a minimizer and we provide a careful analysis of the solvability of the associated Euler{Lagrange equation. Based on these results, and using tools from saddle-point theory and nonlinear analysis, we then show that a Galerkin discretization has a solution that converges to the correct limit (in the case of Dirichlet as well as periodic boundary conditions).
Furthermore, we investigate the issue of optimal convergence rates. Using appropriate dual problems, we can show faster convergence for the energy, the Lagrange multiplier of the underlying minimization problem, and the L2-errors of the solutions. We also look at the dependence of the density functional on the nucleus coordinates and show a convergence result for minimizing nucleus configurations.
These results are subsequently generalized to the case of discretizations with numerical integration. Existence and convergence of solutions, as well as optimal convergence rates can be established if quadrature rules of sufficiently high order are applied.
In the second part of the thesis we consider an atomistic interaction potential in one dimension given through a minimization problem, which gives rise to a field. The forces on atoms are in this case given by local expressions involving this field. A convenient feature of this model is the existence of a weak formulation for the forces, which provides a natural connection point for the coupling with a continuum model. We suggest Quasicontinuum-like coupling mechanisms that are based on a decomposition of the domain into an atomistic and a continuum region. In the continuum region we use an approximation based on the Cauchy{ Born rule. In the atomistic subdomain a version of the atomistic model with Dirichlet boundary conditions is applied. Special attention has to be paid to the dependence of the atomistic subproblem on the boundary and the boundary conditions. Applying concepts from nonlinear analysis we show existence and convergence of solutions to the Quasicontinuum approximation.
An Investigation into the effects of topic and background knowledge of topic on second language speaking performance assessment in language proficiency interviews
Keywords: language testing
second language speaking assessment
Rasch analysis

This study explores, from a test validity perspective, the extent to which the two variables of topic and background knowledge of topic have an effect on spoken performance in language proficiency interviews. It is argued that in assessment contexts where topics are randomly assigned to test takers, it is necessary to demonstrate that topics of tasks and the level of background knowledge that test takers brings to these topics do not exert an undue influence on test results. Otherwise, a validity threat may be introduced to the test.
Data were collected from 82 Farsi speakers of English who performed on ten different topics, across three task types. Participants’ background knowledge of topics was elicited using self- report questionnaires while C-tests were used as a measure of general English language proficiency. Four raters assigned scores to spoken performances using rating scales. Semi- structured interviews were carried out with raters, upon completion of the rating process. A mixed- methods strategy of inquiry was adopted where findings from the quantitative analyses of score data (using Multi-Faceted Rasch Measurement, multiple regression and descriptive statistics) were synthesised with the results of the qualitative analyses of rater interviews and test takers’ content of speech in addressing the foci of the study.
The study’s main findings showed that the topics used in the study exhibited difficulty measures which were statistically distinct i.e. topics, within a given task type, could not be considered parallel. However, the size of the differences in topic difficulties was too small to have a large practical effect on scores. Participants’ different levels of background knowledge were shown to have a consistent, systematic and statistically significant effect on performance with low levels of background knowledge posing the highest level of challenge for test takers and vice versa. Nevertheless, these statistically significant differences in background knowledge levels failed to translate into practically significant differences, as the size of the differences were too small to have a large impact on performance scores. Results indicated that, compared to general language proficiency which accounted for approximately 60% of the variance in spoken performance scores, background knowledge only explained about 1-3% of the variance.
Qualitative analyses of data suggested lack of background knowledge to be associated with topic abandonment, disengagement from topic-related questions, and fewer opportunities for test takers to elaborate on topics. It was also associated with negative affective influence on test takers, particularly lower proficiency individuals. Taken together, the findings have theoretical, methodological and practical implications for second language speaking performance assessment.