Many problems in business, industry, and academia can be modelled as constraint programs consisting of matrices of decision variables. Such “matrix models” often have symmetry. In particular, they often have row and column symmetry as the rows and columns can freely be permuted without affecting the satisfiability of assignments. Existing methods have difficulty in dealing with the super-exponential number of symmetries in a problem with row and column symmetry. We therefore propose some ordering constraints which can effectively break such symmetries. To use these constraints in practice, we develop some efficient linear time propagators. We demonstrate the effectiveness of these symmetry breaking ordering constraints on a wide range of problems. We also show how such ordering constraints can be used to deal with partial symmetries, as well as value symmetries.

Essay 1: Hurst and Lusardi (2004) use higher-order polynomials in wealth in estimating the relationship with entrepreneurship. They find evidence conflicting with the existence of extensive liquidity constraints in the United States. In this paper, their approach is replicated on Swedish data. A positive relationship between wealth and entrepreneurship is found, which supports the liquidity constraints hypothesis. Alternative methods attempting to handle the endogeneity problem and distinguish between absolute decreasing risk aversion and liquidity constraints give further support to the hypothesis. The paper suggests that there exist liquidity constraints in Sweden, which are possibly more extensive than in the United States. Essay 2: Displacement is expected to decrease the reservation wage of self-employment by decreasing earnings in paid employment and increasing the probability of unemployment. This paper examines whether displacement increases the probability of self-employment using propensity score matching on Swedish register-based data. The data include all individuals displaced due to plant closures in 1987 and 1988, and a random sample of 200,000 employed individuals. The results suggest that displacement almost doubles the probability of entering self-employment the year after displacement. A sub-sample analysis indicates that individuals with a potentially worse position on the labor market react more strongly to displacement in terms of entering self-employment. Essay 3: A large literature has studied the effect of displacement on labor market outcomes in general, but no one has evaluated how the displaced succeed as self-employed. This paper studies how the survival of the business is affected by displacement in connection to entry, using a discrete-time proportional hazard model on a matched sample of displaced and non-displaced individuals. The main result of the paper is that, as a consequence of previous displacement, the probability of switching from self-employment to paid employment decreases and the probability of switching to unemployment is unaffected.

"Taxation, Career Concerns and CEO Pay". This paper proposes a simple dynamic model of equilibrium CEO compensation. Motivated by the strengthened career incentives stemming from the fall in the top income tax rates over the past decades, I study the implications of a model where the quality of talent identification depends on how hard individuals work in order to be among the winners in the contest for managerial positions. It is shown how the compensation of CEOs can be interpreted in this light, across time, across industries, and across countries, and I provide some evidence showing that the predictions of the model are in line with several empirical developments over the past decades. "Incentives under Communism: The Value of Low-Quality Goods". In this paper, I study how efficiently centrally planned regimes can provide incentives across different stages of economic development. In particular, I study the attractiveness of an incentive system based on exclusive provision of high-quality goods to high-ranked members of society. At low levels of economic development, a self-interested regime can exploit such an incentive system to reduce the cost of providing incentives. However, such an incentive system generally loses its attractiveness as the economy grows. The economic performance of the centrally planned economies is then analyzed in light of this result. "The Business of Troubled Autocrats". Many autocrats control resource rents. Typically, they rely on these rents in order to buy political support. In this paper, I study how such autocrats behave in product and capital markets, in particular at times of financial distress. The main questions are: How does the asset position of an autocrat affect his behavior as a producer in a market with rents? From whom does the autocrat obtain financing in order to get out of difficulties? I show that when the asset position of the autocrat drops below a certain threshold, output drops below the level of a standard monopolist. Further, the autocrat can obtain less expensive financing domestically by exploiting the presence of vested interests, implying that there is zero foreign debt in equilibrium.

A problem when testing timeliness of event-triggered real-time systems is that response times depend on the execution order of concurrent tasks. Conventional testing methods ignore task interleaving and timing and thus do not help determine which execution orders need to be exercised to gain confidence in temporal correctness. This thesis presents and evaluates a framework for testing of timeliness that is based on mutation testing theory. The framework includes two complementary approaches for mutation-based test case generation, testing criteria for timeliness, and tools for automating the test case generation process. A scheme for automated test case execution is also defined. The testing framework assumes that a structured notation is used to model the real-time applications and their execution environment. This real-time system model is subsequently mutated by operators that mimic potential errors that may lead to timeliness failures. Each mutated model is automatically analyzed to generate test cases that target execution orders that are likely to lead to timeliness failures. The validation of the theory and methods in the proposed testing framework is done iteratively through case-studies, experiments and proof-of-concept implementations. This research indicates that an adapted form of mutation-based testing can be used for effective and automated testing of timeliness and, thus, for increasing the confidence level in real-time systems that are designed according to the event-triggered paradigm.

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Analysis, design and implementation of cooperative control strategies for multi-robot systems under communication constraints is the topic of this thesis. Motivated by a rapidly growing number of applications with networked robots and other vehicles, fundamental limits on the achievable collaborative behavior are studied for large teams of autonomous agents. In particular, a problem is researched in detail in which the group of agents is supposed to agree on a common state without any centralized coordination. Due to the dynamics of the individual agents and their varying connectivity, this problemis an extension of the classical consensus problemin computer science. It captures a crucial component of many desirable features of multi-robot systems, such as formation, flocking, rendezvous, synchronizing and covering. Analytical bounds on the convergence rate to consensus are derived for several systemconfigurations. It is shown that static communication networks that exhibit particular symmetries yield slow convergence, if the connectivity of each agent does not scale with the total number of agents. On the other hand, some randomly varying networks allow fast convergence even if the connectivity is low. It is furthermore argued that if the data being exchanged between the agents are quantized, it may heavily degrade the performance. The extent to which certain quantization schemes are more suitable than others is quantified through relations between the number of agents and the required total network bit rate. The design of distributed coordination and estimation schemes based on the consensus algorithm is presented. A receding horizon coordination strategy utilizing subgradient optimization is developed. Robustness and implementation aspects are discussed. A new collaborative estimation method is also proposed. The implementation of multi-robot control systems is difficult due to the high systemcomplexity. In the final part of this thesis, a hierarchical control architecture appropriate for a class of coordination tasks is therefore suggested. It allows a formal verification of the correctness of the implemented control algorithms. / QC 20100920

I omvårdnaden av dementa uppstår ofta etiska överväganden där hänsyn skall tas till den demenssjuke, närstående, medboende samt lagar och riktlinjer. Sjuksköterskan ställs ofta inför svåra etiska situationer där beslut ska tas om eventuella tvångsåtgärder oberoende av vilket sorts stöd, moraliskt och/eller juridiskt, sjuksköterskan eventuellt har i sina beslut. Syftet med studien var att belysa sjuksköterskors upplevelser av etiska dilemman i demensvården i samband med olika tvångsåtgärder. Data samlades in via fokusgruppsintervjuer med sjuksköterskor (n=12) som ansvarade för personer med demenssjukdom inom särskilda boenden i en kommun i Norrland. En fallbeskrivning utgjorde grunden i fokusgruppsintervjuerna. Materialet analyserades via en kvalitativ manifest innehållsanalys. I resultatet framkom fyra kategorier. Etiska dilemman, etiskt förhållningssätt, rättsnormer och verklighet samt behov av stöd.  Sjuksköterskorna upplevde att de är ensamma i beslutsfattandet och behövde stöd i de svåra besluten kring åtgärder i olika etiska dilemman . Sjuksköterskorna upplevde närståendes delaktighet i vården av de dementa som ett bra och viktigt stöd och dialogen med närstående betonades. Det beskrevs också en känsla av stress då sjuksköterskan kommer i kläm mellan vårdpersonalens och de närståendes motstridiga krav som kan kännas svåra att tillmötesgå. En medvetenhet om de olika lagarna beskrevs men sjuksköterskorna upplevde det inte som ett etiskt dilemma att ibland behöva kringgå dem för att skydda den demente från skada eller lidande. Det skulle dock kännas bättre om de hade möjlighet att få stöd i lagen i sitt handlande. Den slutsats som vi drar är att sjuksköterskorna inte upplever några svårigheter att besluta om en tvångsåtgärd men behovet av stöd och handledning är stort. / Within the care of people with dementia ethical considerations often occurs and considerations has to be taken to the person with dementia, relatives, cohabitants and to laws and guidelines. Ethical dilemmas often occurs when the registered nurses (RNs) have to decide  whether or not to use constraints in the care, regardless of what kind of support these actions have in a moral or legal sense. The aim of this study was to describe the RNs experience of ethical dilemmas in relation to constraints in care of people with dementia. Data were collected in focus groups, with RNs (n=12) who worked in a municipal residential care for people with dementia in the north of Sweden. A case report initiated the interviews. Data were analyzed with qualitative content analysis. Four categories emerged. Ethical dilemmas, ethical approach, legal norms and reality, the need of support.  The RNs experienced loneliness in their decision making of interventions in different ethical difficult care situations and felt the need of support. They experienced that relatives are an important and a fine support in the care and the dialogue are pointed out as important. The RNs described feelings of stress when they were caught between conflicting demands from nursing staff and relatives. The RNs were aware of the laws related to health care, but they didn`t think of it as an ethical dilemma if they had to take sidestep from the law to protect the person with dementia from harm or misery. However they would feel better if they were supported by the law. Conclusion: The RNs didn´t feel any difficulties if they had to decide to use constraints in the care of a person with dementia, but they are in need of support and coaching.

SMEs are established as an important cornerstone for the Swedish economy, due to the amount of people they employ and the economic activity they present. Due to a changing world SMEs are faced with new competition from foreign firms. In order to counter the new environment, an option for the firms is to move abroad, to internationalize. Furthermore China is established as an attractive country for SMEs to expand into, due to the major economic growth. During internationalization the Swedish agency for regional and economic growth identified SMEs to experience a lack of knowledge and capital, which hinders them in their expansion. The paper observes how four different Swedish SMEs, with activity in China moved abroad and how the mentioned lack of capital and knowledge was bridged. A theoretical framework is acquired through established research questions which are meant to analyze the problem description. The firms are identified as Swedish SMEs. In order to acquire empirical data, face to face interviews are conducted with the identified Swedish SMEs. Through the interview the empirical data is gathered, at which point, the paper analyzes the empirical data using the problem statement and the theories previously derived. The paper establishes that the experiential knowledge is the major influence on the resources committed by the firm. The amount of resources committed influences the type of entry mode as well as the accompanied advantages. In affect all firms have limited knowledge and ergo their resources committed are limited. This paper draws the conclusion that due to this, the firms were all able to finance their internationalization and no capital gap was experienced. The firms which were interviewed held experiential knowledge within the firm except one case where it was bridged with the assistance of a consultant. The experiential knowledge is held by individuals and has had a deep impact on the manner of the internationalization. It is identified that the personal relationships between individuals is shown to be of great importance to the firm. The knowledge constraints were bridged by the individuals’ experiential knowledge.

Consistent, accurate and timely data are essential to the functioning of a modern organization. Managing the integrity of an organization’s data assets in a systematic manner is a challenging task in the face of continuous update, transformation and processing to support business operations. Classic approaches to constraint-based integrity focus on logical consistency within a database and reject any transaction that violates consistency, but leave unresolved how to fix or manage violations. More ad hoc approaches focus on the accuracy of the data and attempt to clean data assets after the fact, using queries to flag records with potential violations and using manual efforts to repair. Neither approach satisfactorily addresses the problem from an organizational point of view. In this thesis, we provide a conceptual model of constraint-based integrity management (CBIM) that flexibly combines both approaches in a systematic manner to provide improved integrity management. We perform a gap analysis that examines the criteria that are desirable for efficient management of data integrity. Our approach involves creating a Data Integrity Zone and an On Deck Zone in the database for separating the clean data from data that violates integrity constraints. We provide tool support for specifying constraints in a tabular form and generating triggers that flag violations of dependencies. We validate this by performing case studies on two systems used to manage healthcare data: PAL-IS and iMED-Learn. Our case studies show that using views to implement the zones does not cause any significant increase in the running time of a process.

Biological invasions provide opportunities to study evolutionary processes occurring during contemporary time scales. Here, I combine a literature review of common garden studies of invasive plant species, with field and glasshouse experiments on populations of the outcrossing, perennial, wetland invader Lythrum salicaria (purple loosestrife - Lythraceae), to investigate the evolutionary genetics of local adaptation in reproductive and life-history traits. A review of 32 common garden studies of 28 introduced species identified previously unrecognized latitudinal clines in phenotypic traits in both native and introduced populations. To obtain direct evidence for clinal variation and local adaptation, I investigated populations of L. salicaria sampled along a latitudinal gradient of growing season length in eastern North America. Controlled pollinations of plants from 12 populations provided no evidence for the breakdown of self-incompatibility to self-compatibility towards the northern range limit. However, a quantitative genetic experiment involving 20 populations revealed latitudinal clines in population mean, variance and skew for days to flower and vegetative size. Broad-sense estimates of genetic variance were significant for most traits; however, strong inter-correlations among traits suggested that fitness trade-offs have constrained population divergence. The observed clines supported a model of selection for early flowering in northern populations constrained by a trade-off between age and size at flowering. A comparison of variance-covariance matrices of family and population means (G and D, respectively) of life-history traits demonstrated that populations have evolved in response to selection under genetic constraints, rather than through neutral processes. A reciprocal transplant experiment involving six populations and three common gardens spanning the latitudinal range provided direct evidence for local adaptation in flowering phenology. Populations maintained the same rank-order for time to flowering and vegetative size at each site, and southern populations had the highest fecundity at the southern site but the lowest at the northern site. Finally, a phenotypic selection analysis in each common garden involving 61 F2 families of crosses between a northern × southern populations confirmed that selection favours earlier flowering in northern populations. These results demonstrate that natural selection on reproductive phenology has accompanied the invasive spread of L. salicaria in eastern N. America.