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In this study, I introduce the alternative-dependent focal Luce model (ADFLM), a random choice model generalizing the well-known Luce model (1959). In the ADFLM, focal alternatives are chosen more frequently relative to their utilities. I identify utilities, focal sets, and the magnitude of focal biases from choice data. Additionally, I axiomatically characterize the ADFLM by weakening the independence of irrelevant alternatives (IIA) axiom. This model can explain the well-known behavioral phenomena, the attraction and compromise effects. Furthermore, I also study the seller's profit maximization problem in the ADFLM. I also study an asymmetric dynamic patent race with a deadline under complete information. In my model, two firms decide whether to invest in RandD. The patent arrives randomly according to a Poisson process, and the large firm has a higher hazard rate than the small firm. I find the unique sub-game perfect Nash equilibrium strategy for this game. At the equilibrium, the large firm will stay longer in the race, while the small firm will quit earlier. The large firm's optimal stopping time is not affected by the competition, while the small firm's stopping time is reduced. Additionally, I find that companies will remain longer in the race if the investigation cost is lower, the winning premium is higher, the deadline is extended further, and the hazard rate is more prominent. Moreover, the market becomes more efficient with the competition since the patent is easier to realize. / Doctor of Philosophy / In this research, I study the consumer's behavior when individuals have limited cannot or do not give the same attention to each alternative available to them. In my study, I characterize the alternative-dependent focal Luce model (ADFLM), a consumer behavior model. Moreover, I solve the seller's profit maximization problem when the consumer's behavior follows the ADFLM. Meanwhile, I also study a dynamic patent race problem that occurs when firms compete for a patent with a deadline. If no firms achieve the patent, the stopping time (when the firm quits the patent race) of the large firm's (with a higher success rate every period) is not affected by the introduction of the small firm. However, the small firm quits earlier when the large firm is introduced. The competition between the two companies increases the overall probability of receiving a patent.

Yes / That organizations exist in a fluid environment of unprecedented and discontinuous change seems beyond debate. We seem to find ourselves immersed in a world in which events have a tendency to unfold and overtake us in unforeseeable and novel ways that defy comprehension; a crisis of meaning takes place and conventional sensemaking is disrupted. Our need to imaginatively construct new meanings that allow us to understand what is going on and to work out how to respond becomes ever more pressing. We do live in interesting times. The emergence of the new, however, challenges current established ways of knowing and opens a creative space for radical learning to take place. Novelty stimulates the generative process by which organizations and individuals learn, adapt to and cope with the exigencies they face in order to survive and progress. Such radical learning occurs when creative linguistic interventions in dialogue opens up semantic spaces whereby new terms are coined and old ones broken up, combined and/or redeployed in novel ways, in an effort to give expression to the fresh circumstances experienced or new phenomena observed. We call this kind of imaginative linguistic intervention semantic transformation. In this paper we argue that it is this semantic transformation that promotes radical transformational learning. Such semantic transformation is predicated on the improvisatory character of dialogue as a form of communication. We explore how, through this dialogical process of semantic transformation, we discover the resources and means to respond to the vagueness and equivocality experienced, by exploiting language in novel ways in our attempts to make sense of and account for such experiences.

This dissertation explores the interaction between modality and aspect in Makkan Arabic (MA). There is some consensus in the semantic literature regarding the treatment of modal expressions that may obtain various flavours, such as epistemic, deontic, bouletic, ability, necessity or teleological. These various modal flavours can be captured by a unified lexical entry, and are identified by contextual factors Kratzer (1977, 1981, 1991, 2012). There is some debate regarding the structural location of modal elements, some of which have been argued to be high (the case of epistemic modals) and others low (the case of root modals) (e.g. Cinque (1999)). The relative scope of modals has been subject of much recent work on modality, in particular in relation to their interaction with temporal categories such as aspect. This thesis investigates this topic on the basis of novel data from MA. I observe that the flavour of modality can change depending on how it is inflected with different types of aspect in MA. This observation is in line of Hacquard; Hacquard; Hacquard’s (2006; 2009; 2014) proposal for French and Italian. In MA, when the root modal \gdr\ “can” is inflected with the perfective, the combination yields entailments that have come to be known in the literature as ‘actuality entailments’ (AEs) (see Bhatt (1999, 2006)). In this case, the speaker gives rise to the inference that the proposition expressed by the complement holds in the actual world (instead of merely in some possible but not actual world). My thesis integrates the case of \gdr\ to current cross-linguistic debates on this topic. Building on Hacquard’s work, I argue that AEs are generated when perfective aspect scopes over root modals. Perfective aspect links events to the actual world. Imperfective aspect scoping over the modal fails to generate AEs. My thesis ex- ii tends the investigation of AEs to non-perfective cases. I argue that in addition to the contrast between perfective and imperfective, MA also distinguishes perfect aspect (e.g. an auxiliary plus a modal participle like gaadir). I suggest that the perfect in MA has several shapes, including the choice between two auxiliaries: kaan and saar. I link the different shapes of the perfect to the different types of interpretation identified by Portner (2000, 2003) for the English perfect. I suggest that in MA, different forms of the perfect are linked to distinct interpretations (which in English are grouped together under one form). In addition I show that, contrary to what has been argued by Hacquard for French, the perfect in MA can give rise to AEs in the case of the saar auxiliary. I develop an analysis of the saar perfect that is inspired by Hacquard’s proposal for perfective: in the case of saar, contrary to kaan, the perfect links the eventuality to the actual world. While the discussion of AEs in relation to the modal \gdr\ are linked to the proposal that aspect scopes over the modal, I also examine the case of a modal expression that scopes over aspect: qad “might”. I show that in spite of the fact that aspect scopes below the modal, the contrast between perfective and imperfective in the embedded clause can still give rise to differences in the generation of AEs. This case is interesting because much previous literature on AEs has focused on languages in which aspect scopes over the modal. MA qad provides an example where the modal scopes over aspect, and it is still the case that AEs appear to be generated. In spite of the structural differences with \gdr\, my analysis of qad builds on Hacquard’s proposal for AEs with the perfective, appealing to her proposal for the ‘preservation of event description’ to account for the fact that properties of eventualities can remain stable across worlds. The structure of the thesis is as follows: Chapter 1 provides an introduction to the empirical domain, situating aspect and modality in the description of MA; in addition it iii provides an introduction to key theoretical concepts to be used in later chapters. Chapter 2 discusses AEs in the case of the root modal \gdr\, comparing perfective and imperfective. Chapter 3 extends the discussion of the modal to examples with the perfect, distinguishing between the kaan- and saar- perfects. Chapter 4 investigates the behaviour of qad and its interaction with perfective and imperfective complements. Chapter 5 offers a brief summary and concluding remarks.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This paper presents the implementation of an artificial magnetic ground-plane with a low profile Log-periodic Dipole Array (LPDA) antennas. After the properties of three typical Electromagnetic Bandgap (EBG) structures are investigated and their bandwidth properties are studied, a mechanism is presented to improve the band-width over which the EBG surface acts as a perfect magnetic conductor (PMC). A low profile LPDA is modeled above this surface and the results indicate an improved band-width region. Compared with a LPDA in free space the frequency band is shifted higher by the EBG surface and the gain pattern is shifted from a horizontal orientation to a vertical orientation. / AFRIKAANSE OPSOMMING: Hierdie dokument stel voor die implementering van kunsmatige magnetiese grondvlakke met Logaritmiese Periodiese Dipool Samestelling (LPDS) antennas. Die eienskappe van drie tipiese Elektromagnetiese Bandgaping (EBG) strukture word ondersoek en hul bandwydte eienskappe word bestudeer. ’n Meganisme word voorgestel om die bandwydte te verbeter waar die EBG oppervlakte soos n perfekte magnetiese geleier optree. ’n Lae profiel LPDS word bo hierdie oppervlakte geplaas. Die resultate dui aan ’n verbetering in the bandwydte. In vergelyking met ’n LPDS in vrye ruimte skuif die frekwensie band ho¨er as gevolg van die EBG oppervlakte en die aanwins patroon skuif van ’n horisontale orientasie na ’n vertikale orientasie.

There is an increasing need for accurate models describing the electrical behaviour of individual biological cells exposed to electromagnetic fields. In this area of solving linear problem, the most frequently used technique for computing the EM field is the Finite-Difference Time-Domain (FDTD) method. When modelling objects that are small compared with the wavelength, for example biological cells at radio frequencies, the standard Finite-Difference Time-Domain (FDTD) method requires extremely small time-step sizes, which may lead to excessive computation times. The problem can be overcome by implementing a quasi-static approximate version of FDTD, based on transferring the working frequency to a higher frequency and scaling back to the frequency of interest after the field has been computed. An approach to modeling and analysis of biological cells, incorporating the Hodgkin and Huxley membrane model, is presented here. Since the external medium of the biological cell is lossy material, a modified Berenger absorbing boundary condition is used to truncate the computation grid. Linear assemblages of cells are investigated and then Floquet periodic boundary conditions are imposed to imitate the effect of periodic replication of the assemblages. Thus, the analysis of a large structure of cells is made more computationally efficient than the modeling of the entire structure. The total fields of the simulated structures are shown to give reasonable and stable results at 900MHz, 1800MHz and 2450MHz. This method will facilitate deeper investigation of the phenomena in the interaction between EM fields and biological systems. Moreover, the nonlinear response of biological cell exposed to a 0.9GHz signal was discussed on observing the second harmonic at 1.8GHz. In this, an electrical circuit model has been proposed to calibrate the performance of nonlinear RF energy conversion inside a high quality factor resonant cavity with known nonlinear device. Meanwhile, the first and second harmonic responses of the cavity due to the loading of the cavity with the lossy material will also be demonstrated. The results from proposed mathematical model, give good indication of the input power required to detect the weakly effects of the second harmonic signal prior to perform the measurement. Hence, this proposed mathematical model will assist to determine how sensitivity of the second harmonic signal can be detected by placing the required specific input power.

當政策當局之目標，期使實際之實質產出水準，與充份訊息下Walrasian 均衡之實質 產出水準兩者之離差，所構成之二次損失函數達到極小。當實際之實質產出等于充分 訊息之實質產出水準，由于完全排除干擾項對此二次損失函數之衝擊， Turnovsky (1987) 稱此特性為“完全安定性” (Perfect Stabilization)。 Bean(1983),Brandley and Jansen(1989)提出：當政策當局能夠成功地盯住名目國民 所得，可以達成完全安定性。然而，該二文中并未提出，應以何種政策方式盯住名目 國民所得目標標 本文補充Bean(1983),Brandley and Jansen(1989)的主張，并討論不同的干擾項發生 時間，政府所采行之盯住名目國民所得的方式，也將有所不同。本文得到： （１）當干擾項發生在期初，政府與私人部門皆可在決策之前觀察到，不管盯住特定 水準之名目國民所得，或只干擾其波動，必然可達成完全安定性。 （２）當干擾發生在政府決策之后，與私人決策之前，則政府所采行之盯住政策，只 能以政策干擾名目國民所得之波動，而無法如Brandley and Jansen 將名目國民所得 目標盯住于特定水準。 （３）當政府與私人部門皆無法觀察到干擾項，則政府采行之盯住政策，只能以政策 干擾名目國民所得之波動，無法如Brandley and Jansen,盯住在一特定水準之名目國 民所得目標。而且，不論以何種型式之盯住策略，皆可達成完全安定性。

A Probabilistically Checkable Proof (PCP) of a mathematical statement is a proof written in a special manner that allows for efficient probabilistic verification. The celebrated PCP Theorem states that for every family of statements in NP, there is a probabilistic verification procedure that checks the validity of a PCP proof by reading only 3 bits from it. This landmark theorem, and the works leading up to it, laid the foundation for many subsequent works in computational complexity theory, the most prominent among them being the study of inapproximability of combinatorial optimization problems. This thesis focuses on a broad class of combinatorial optimization problems called Constraint Satisfaction Problems (CSPs). In an instance of a CSP problem of arity k, we are given a set of variables taking values from some finite domain, and a set of constraints each involving a subset of at most k variables. The goal is to find an assignment that simultaneously satisfies as many constraints as possible. An alternative formulation of the goal that is commonly used is Gap-CSP, where the goal is to decide whether a CSP instance is satisfiable or far from satisfiable, where the exact meaning of being far from satisfiable varies depending on the problems.We first study Boolean CSPs, where the domain of the variables is {0,1}. The main question we study is the hardness of distinguishing satisfiable Boolean CSP instances from those for which no assignment satisfies more than some epsilon fraction of the constraints. Intuitively, as the arity increases, the CSP gets more complex and thus the hardness parameter epsilon should decrease. We show that for Boolean CSPs of arity k, it is NP-hard to distinguish satisfiable instances from those that are at most 2^{~O(k^{1/3})}/2^k-satisfiable. We also study coloring of graphs and hypergraphs. Given a graph or a hypergraph, a coloring is an assignment of colors to vertices, such that all edges or hyperedges are non-monochromatic. The gap problem is to distinguish instances that are colorable with a small number of colors, from those that require a large number of colors. For graphs, we prove that there exists a constant K_0&gt;0, such that for any K &gt;= K_0, it is NP-hard to distinguish K-colorable graphs from those that require 2^{Omega(K^{1/3})} colors. For hypergraphs, we prove that it is quasi-NP-hard to distinguish 2-colorable 8-uniform hypergraphs of size N from those that require 2^{(log N)^{1/4-o(1)}} colors. In terms of techniques, all these results are based on constructions of PCPs with perfect completeness, that is, PCPs where the probabilistic proof verification procedure always accepts a correct proof. Not only is this a very natural property for proofs, but it can also be an essential requirement in many applications. It has always been particularly challenging to construct PCPs with perfect completeness for NP statements due to limitations in techniques. Our improved hardness results build on and extend many of the current approaches. Our Boolean CSP result and GraphColoring result were proved by adapting the Direct Sum of PCPs idea by Siu On Chan to the perfect completeness setting. Our proof for hypergraph coloring hardness improves and simplifies the recent work by Khot and Saket, in which they proposed the notion of superposition complexity of CSPs. / Ett probabilistiskt verifierbart bevis (eng: Probabilistically Checkable Proof, PCP) av en matematisk sats är ett bevis skrivet på ett speciellt sätt vilket möjliggör en effektiv probabilistisk verifiering. Den berömda PCP-satsen säger att för varje familj av påståenden i NP finns det en probabilistisk verifierare som kontrollerar om en PCP bevis är giltigt genom att läsa endast 3 bitar från det. Denna banbrytande sats, och arbetena som ledde fram till det, lade grunden för många senare arbeten inom komplexitetsteorin, framförallt inom studiet av approximerbarhet av kombinatoriska optimeringsproblem. I denna avhandling fokuserar vi på en bred klass av optimeringsproblem i form av villkorsuppfyllningsproblem (engelska ``Constraint Satisfaction Problems'' CSPs). En instans av ett CSP av aritet k ges av en mängd variabler som tar värden från någon ändlig domän, och ett antal villkor som vart och ett beror på en delmängd av högst k variabler. Målet är att hitta ett tilldelning av variablerna som samtidigt uppfyller så många som möjligt av villkoren. En alternativ formulering av målet som ofta används är Gap-CSP, där målet är att avgöra om en CSP-instans är satisfierbar eller långt ifrån satisfierbar, där den exakta innebörden av att vara ``långt ifrån satisfierbar'' varierar beroende på problemet.Först studerar vi booleska CSPer, där domänen är {0,1}. Den fråga vi studerar är svårigheten av att särskilja satisfierbara boolesk CSP-instanser från instanser där den bästa tilldelningen satisfierar högst en andel epsilon av villkoren. Intuitivt, när ariten ökar blir CSP mer komplexa och därmed bör svårighetsparametern epsilon avta med ökande aritet. Detta visar sig vara sant och ett första resultat är att för booleska CSP av aritet k är det NP-svårt att särskilja satisfierbara instanser från dem som är högst 2^{~O(k^{1/3})}/2^k-satisfierbara. Vidare studerar vi färgläggning av grafer och hypergrafer. Givet en graf eller en hypergraf, är en färgläggning en tilldelning av färger till noderna, så att ingen kant eller hyperkant är monokromatisk. Problemet vi analyserar är att särskilja instanser som är färgbara med ett litet antal färger från dem som behöver många färger. För grafer visar vi att det finns en konstant K_0&gt;0, så att för alla K &gt;= K_0 är det NP-svårt att särskilja grafer som är K-färgbara från dem som kräver minst 2^{Omega(K^{1/3})} färger. För hypergrafer visar vi att det är kvasi-NP-svårt att särskilja 2-färgbara 8-likformiga hypergrafer som har N noder från dem som kräv minst 2^{(log N)^{1/4-o(1)}} färger. Samtliga dessa resultat bygger på konstruktioner av PCPer med perfekt fullständighet. Det vill säga PCPer där verifieraren alltid accepterar ett korrekt bevis. Inte bara är detta en mycket naturlig egenskap för PCPer, men det kan också vara ett nödvändigt krav för vissa tillämpningar. Konstruktionen av PCPer med perfekt fullständighet för NP-påståenden ger tekniska komplikationer och kräver delvis utvecklande av nya metoder. Vårt booleska CSPer resultat och vårt Färgläggning resultat bevisas genom att anpassa ``Direktsumman-metoden'' introducerad av Siu On Chan till fallet med perfekt fullständighet. Vårt bevis för hypergraffärgningssvårighet förbättrar och förenklar ett färskt resultat av Khot och Saket, där de föreslog begreppet superpositionskomplexitet av CSP. / <p>QC 20150916</p>

For a number of unsolved problems in graph theory such as the cycle double cover conjecture, Fulkerson's conjecture and Tutte's 5-flow conjecture it is sufficient to prove them for a family of graphs called snarks. Named after the mysterious creature in Lewis Carroll's poem, a \emph{snark} is a cyclically 4-edge connected 3-regular graph of girth at least 5 which cannot be properly edge coloured using three colours. Snarks and problems for which an edge minimal counterexample must be a snark are the central topics of this thesis.   The first part of this thesis is intended as a short introduction to the area. The second part is an introduction to the appended papers and the third part consists of the four papers presented in a chronological order. In Paper I we study the strong cycle double cover conjecture and stable cycles for small snarks. We prove that if a bridgeless cubic graph $G$ has a cycle of length at least $|V(G)|-9$ then it also has a cycle double cover. Furthermore we show that there exist cyclically 5-edge connected snarks with stable cycles and that there exists an infinite family of snarks with stable cycles of length 24. In Paper II we present a new algorithm for generating all non-isomorphic snarks with a given number of vertices. We generate all snarks on 36 vertices and less and study these with respect to various properties. We find that a number of conjectures on cycle covers and colourings holds for all graphs of these orders. Furthermore we present counterexamples to no less than eight published conjectures on cycle coverings, cycle decompositions and the general structure of regular graphs.     In Paper III we show that Jaeger's Petersen colouring conjecture holds for three infinite families of snarks and that a minimum counterexample to this conjecture cannot contain a certain subdivision of $K_{3,3}$ as a subgraph. Furthermore, it is shown that one infinite family of snarks have strong Petersen colourings while another does not have any such colourings. Two simple constructions for snarks with arbitrary high oddness and resistance is given in Paper IV. It is observed that some snarks obtained from this construction have the property that they require at least five perfect matchings to cover the edges. This disproves a suggested strengthening of Fulkerson's conjecture.

The primary goal of this study was to determine the impact of price discrimination on tourism demand. Four objectives were defined with reference to the primary research goal. The first objective was to analyse the concept of price discrimination and relevant theories by means of a literature study. In this regard it was found that price discrimination between markets is fairly common and that it occurs if the same goods were sold to different customers at different prices. Price discrimination is also possible as soon as some monopoly power exists and it is feasible when it is impossible or at least impractical for the buyers to trade among themselves. Three different kinds of price discrimination can be applied, namely first-degree, second-degree and third-degree price discrimination. The data also indicated that price discrimination is advantageous (it mainly increases profit) and that it has several other effects too. The second objective was to analyse examples of price discrimination by means of international case studies. In these different case studies it was found that demand and supply, therefore consumer and product, formed the basis of price discrimination. If demand did not exist, it would be impossible to apply price discrimination. The findings also indicated that, for an organisation to be able to practice price discrimination, the markets must be separated effectively and it will only be successful if there is a significant difference in demand elasticity between the different consumers. Furthermore, the ability to charge these different prices will depend on the consumer's ability and willingness to pay. If an organisation should decide to price discriminate, it would lead to a higher profit, a more optimal pricing policy and also to an increase in sales. The third objective was to analyse national case studies. This was done through comparing the data of a tourism organisation price discriminating (Mosetlha Bush Camp, situated in the North West) to two organisations that did not implement price discrimination (Kgalagadi Transfrontier Park in the Northern Cape and Golden Leopard Resort, also situated in the North West). It was found that a customer with low price elasticity is less deterred by a higher price than a customer with a high price elasticity of demand. As long as the customer's price elasticity is less than one, it will be very advantageous to increase the price: the seller will in this case get more money for less goods. With the increase in price the price elasticity tends to rise above one. The fourth objective was to draw conclusions and make recommendations. It was concluded that price discrimination could be applied successfully in virtually any organisation or industry. Furthermore, price discrimination does not always have a negative effect; but can have a positive ass well. It can have a positive effect on tourism demand. The findings emphasised that the main reason for implementing price discrimination is to increase profit at the cost of reducing consumer surplus. From the results it was recommended that more research on this topic should be conducted. / Thesis (M.Com. (Tourism))--North-West University, Potchefstroom Campus, 2006.