Locality : A useful notion for proving inexpressibility in Finite Model Theory

This thesis discusses the notion of locality used in finite model theory to obtain results about the expressive power of first order logic. It turns out that the most commonly used Ehrenfeucht-Fraïssé games are also applicable over finite structures. However, we analyze with an example the need for simpler tools for finite structures due to the complex combinatorial arguments required while using EF-games. We argue that locality is such a tool, although the gap between games and locality is quite narrow as the latter is in fact based on the former. Intuitively speaking: locality of FO implies that in order to check the satisfiability of a FO formula over a finite structure, it is enough to look at a small portion of the universe (which will be called the neighborhood of a point). We discuss two commonly known notions of locality given by William Hanf and Haim Gaifman. We provide the original results of the authors and then their modified versions suitable for finite structures. We then show that first order logic over any relational vocabulary has both of these locality properties. In order to grasp the idea of locality we also include examples wherever required. Towards the end of the thesis we also discuss deficiencies and limitations of the two types of locality and possible solutions to overcome them. In the last section we also discuss locality of order-invariant first order formulas

Parameterized aspects of team-based formalisms and logical inference

Parameterized complexity is an interesting subfield of complexity theory that has received a lot of attention in recent years. Such an analysis characterizes the complexity of (classically) intractable problems by pinpointing the computational hardness to some structural aspects of the input. In this thesis, we study the parameterized complexity of various problems from the area of team-based formalisms as well as logical inference. In the context of team-based formalism, we consider propositional dependence logic (PDL). The problems of interest are model checking (MC) and satisfiability (SAT). Peter Lohmann studied the classical complexity of these problems as a part of his Ph.D. thesis proving that both MC and SAT are NP-complete for PDL. This thesis addresses the parameterized complexity of these problems with respect to a wealth of different parameterizations. Interestingly, SAT for PDL boils down to the satisfiability of propositional logic as implied by the downwards closure of PDL-formulas. We propose an interesting satisfiability variant (mSAT) asking for a satisfiable team of size m. The problem mSAT restores the ‘team semantic’ nature of satisfiability for PDL-formulas. We propose another problem (MaxSubTeam) asking for a maximal satisfiable team if a given team does not satisfy the input formula. From the area of logical inference, we consider (logic-based) abduction and argumentation. The problem of interest in abduction (ABD) is to determine whether there is an explanation for a manifestation in a knowledge base (KB). Following Pfandler et al., we also consider two of its variants by imposing additional restrictions over the size of an explanation (ABD and ABD=). In argumentation, our focus is on the argument existence (ARG), relevance (ARG-Rel) and verification (ARG-Check) problems. The complexity of these problems have been explored already in the classical setting, and each of them is known to be complete for the second level of the polynomial hierarchy (except for ARG-Check which is DP-complete) for propositional logic. Moreover, the work by Nord and Zanuttini (resp., Creignou et al.) explores the complexity of these problems with respect to various restrictions over allowed KBs for ABD (ARG). In this thesis, we explore a two-dimensional complexity analysis for these problems. The first dimension is the restrictions over KB in Schaefer’s framework (the same direction as Nord and Zanuttini and Creignou et al.). What differentiates the work in this thesis from an existing research on these problems is that we add another dimension, the parameterization. The results obtained in this thesis are interesting for two reasons. First (from a theoretical point of view), ideas used in our reductions can help in developing further reductions and prove (in)tractability results for related problems. Second (from a practical point of view), the obtained tractability results might help an agent designing an instance of a problem come up with the one for which the problem is tractable

Financial Leverage Decision in Cement Sector of Pakistan

This paper attempts to understand the behaviour of firms in cement sector of Pakistan regarding its financial structure decision. A typical firm will consider various factors before it adopts a specific blend of liability and equity in its capital structure. This paper uses four factors named as tangibility, profitability, size and growth. Panel data analysis is adopted to check the relationship of these factors with financial leverage for the period of 1999 to 2014. The results are explained considering existing but competing theories. It is observed that profitability and tangibility have significant relation with capital structure decision. These relationships can be explained with the existing theories, however, there was not enough evidence to consider any of the theories as superior

Parameterised Complexity of Propositional Inclusion and Independence Logic

In this work we analyse the parameterised complexity of propositional inclusion (PINC) and independence logic (PIND). The problems of interest are model checking (MC) and satisfiability (SAT). The complexity of these problems is well understood in the classical (non-parameterised) setting. Mahmood and Meier (FoIKS 2020) recently studied the parameterised complexity of propositional dependence logic (PDL). As a continuation of their work, we classify inclusion and independence logic and thereby come closer to completing the picture with respect to the parametrised complexity for the three most studied logics in the propositional team semantics setting. We present results for each problem with respect to 8 different parameterisations. It turns out that for a team-based logic L such that L-atoms can be evaluated in polynomial time, then MC parameterised by teamsize is FPT. As a corollary, we get an FPT membership under the following parameterisations: formula-size, formula-depth, treewidth, and number of variables. The parameter teamsize shows interesting behavior for SAT. For PINC, the parameter teamsize is not meaningful, whereas for PDL and PIND the satisfiability is paraNP-complete. Finally, we prove that when parameterised by arity, both MC and SAT are paraNP-complete for each of the considered logics.Comment: A revised versio

Financial Leverage Decision in Cement Sector of Pakistan

This paper attempts to understand the behaviour of firms in cement sector of Pakistan regarding its financial structure decision. A typical firm will consider various factors before it adopts a specific blend of liability and equity in its capital structure. This paper uses four factors named as tangibility, profitability, size and growth. Panel data analysis is adopted to check the relationship of these factors with financial leverage for the period of 1999 to 2014. The results are explained considering existing but competing theories. It is observed that profitability and tangibility have significant relation with capital structure decision. These relationships can be explained with the existing theories, however, there was not enough evidence to consider any of the theories as superior

Role of Customer Participation in Technology Innovation in Higher Education Institutions (HEIs): A Qualitative Study on Value Co-Creation and Co-Destruction

Bringing innovation to organizations is not only considered to be a growth strategy but also a way to survive in the current technological era. Technological innovation involves customer participation and engagementfor value co-creation and co-destruction, which raises new challenges in theory and practice. It becomes more challenging in the service industry, specifically the education sector. Limited literature is available regardingdifferent roles played by the participating customers during technology innovation. Therefore, an empirical study was needed to explore the role(s) of customer participation in the entire process of co-creation, the drivers for customers’ positive engagement, and the reasons behind the negative engagement of customers while participating in technology innovation process. The negative engagement of the customers not only hinders the success of the co-creation process, rather it also causes co-destruction from multiple aspects. The current study followed the qualitative method to explore the phenomenon of value co-creation and co-destruction. In order to perform this task, semi-structured in-depth interviews were conducted with the representatives of Information and Communication Technologies (ICT) firms and Higher Education Institutions (HEIs) of Pakistan. The collected qualitative data was sorted in Nvivo 13 and thematic analysis wasperformed. The study concluded with the identification of multiple roles/dimensions of customer participation to foster or hinder the cocreation process. The major beneficiaries of the study include ICT firms and HEIs which need to re-assess their business processes. The study also contributes to the evolving theory of value co creation, while engaging the actors (customers)

A parameterized view on the complexity of dependence and independence logic

In this paper, we investigate the parameterized complexity of model checking for Dependence and Independence logic, which are well studied logics in the area of Team Semantics. We start with a list of nine immediate parameterizations for this problem, namely the number of disjunctions (i.e. splits)/(free) variables/universal quantifiers, formula-size, the tree-width of the Gaifman graph of the input structure, the size of the universe/team and the arity of dependence atoms. We present a comprehensive picture of the parameterized complexity of model checking and obtain a division of the problem into tractable and various intractable degrees. Furthermore, we also consider the complexity of the most important variants (data and expression complexity) of the model checking problem by fixing parts of the input.Peer reviewe

Risk Factors of Subependymal Hemorrhage-Intraventricular Haemorrhage in Preterm Infants

To determine the frequency and peaktime of occurrence of subependymal hemorrhageintraventricularhemorrhage (SEH-IVH) in preterminfants and to identify the predisposing risk factors.Methods: In this descriptive study consecutive liveborn babies (n=135), between the gestational ages of28-34 weeks, were enrolled. Information regardingweight, gestational age, mode of delivery andpresence of risk factors were recorded. Each newbornunderwent cranial ultrasound on designated daysand was followed up till the fourth week of lifeunless expired.Results: The frequency of SEH-IVH was found tobe 20.8%. The most vulnerable group in terms ofgestational age and weight were infants < 32 wksand weighing < 1.5 kg respectively. The peak age ofoccurrence of SEH-IVH was first three days of life.Risk factors found to be associated with SEH-IVHwere RDS with ventilation, exchange transfusionand thrombocytopenia.Conclusion: The incidence of SEH-IVH in infantsbetween 28-34 wks gestation is significantly high.The crucial period is the first three days of life andrespiratory distress syndrome (RDS) withventilation, exchange transfusion andthrombocytopenia carry the highest risk ofhemorrhage. There is a need to emphasize on theprevention of prematurity and optimum perinatalmanagement to minimize the risk of hemorrhage