Detta är en studie om elevernas attityder till teoretiska och praktiska läxor. Intresset vaknade hos oss efter vår verksamhetsförlagda utbildning (VFU) och den egna skolgången. Alla elever har olika sätt att lära sig och vi som pedagoger skall ju sträva efter att individanpassa undervisningen. Vi tror att en praktisk läxa skulle kunna stimulera flera elevers sätt att lära sig. Det är både en kvalitativ och kvantitativ studie. Vår studie är även experimentell eftersom vi har tre grupper som gjort en teoretisk läxa och tre grupper som även gjorde en praktisk läxa inför ett läxförhör, båda grupperna är lika viktiga i vår studie. Vi har sedan undersökt vilka attityder eleverna har till teoretiska och praktiska läxor genom att lämna ut en enkät för att mäta elevernas attityder till teoretisk och praktisk läxa. Studien kommer att genomfördes i årskurs åtta. Vi är väl medvetna om att studiens resultat inte går att generalisera. Vi jämförde även läxförhöret med ett förhör som gjorts tidigare. Vi avslutade sedan med en intervju med läraren till eleverna för att fråga, vad läraren anser om läxförhören och praktiska läxor, samt om de praktiska läxorna kan ha påverkat resultaten eller inte. Vi vill med studien testa vårt antagande om praktiska läxor kan stimulera elevers olika sätt att lära sig. Studien visar att elevernas attityder till läxor är att de föredrar en variation av både teoretiska och praktiska läxor. / This is a study about attitudes to theoretical and practical homework. Our interest in the subject emerged during our practical teacher training but is also influenced from our own VFU "practical teacher training" and our own time in school. All students have different ways of learning and as pedagogues we ought to try to individualize the education. We believe a practical homework could stimulate the students' different ways of learning. This is both a qualitative and a quantitative study. Our study is also experimental because we got three groups that did theoretical homework and three groups that, in addition, did a practical homework before a test. Both groups are important to our study. Then we examined which attitudes the students had to theoretical and practical homework by the means of a questionnaire, which measured the students attitudes to practical and theoretical homework. The study will be made in eight class. We are well aware that you can not generalize. We also compared the test with a test the students did previously, before are study took place. We completed the study with an interview with the students teacher in order to ask what she considered about the test results and practical homework. And if she believes the practical homework affects the result of the test. By this study we try the hypothesis that practical homework can stimulate students in their different ways of learning. The study shows that the students prefer a variation of both theoretical and practical homework.

Network coding has emerged as a new paradigm for communication in networks, allowing packets to be algebraically combined at internal nodes, rather than simply routed or replicated. The very nature of packet-mixing, however, makes the system highly sensitive to error propagation. Classical error correction approaches are therefore insufficient to solve the problem, which calls for novel techniques and insights. The main portion of this work is devoted to the problem of error control assuming an adversarial or worst-case error model. We start by proposing a general coding theory for adversarial channels, whose aim is to characterize the correction capability of a code. We then specialize this theory to the cases of coherent and noncoherent network coding. For coherent network coding, we show that the correction capability is given by the rank metric, while for noncoherent network coding, it is given by a new metric, called the injection metric. For both cases, optimal or near-optimal coding schemes are proposed based on rank-metric codes. In addition, we show how existing decoding algorithms for rank-metric codes can be conveniently adapted to work over a network coding channel. We also present several speed improvements that make these algorithms the fastest known to date. The second part of this work investigates a probabilistic error model. Upper and lower bounds on capacity are obtained for any channel parameters, and asymptotic expressions are provided in the limit of long packet length and/or large field size. A simple coding scheme is presented that achieves capacity in both limiting cases. The scheme has fairly low decoding complexity and a probability of failure that decreases exponentially both in the packet length and in the field size in bits. Extensions of the scheme are provided for several variations of the channel. A final contribution of this work is to apply rank-metric codes to a closely related problem: securing a network coding system against an eavesdropper. We show that the maximum possible rate can be achieved with a coset coding scheme based on rank-metric codes. Unlike previous schemes, our scheme has the distinctive property of being universal: it can be applied on top of any communication network without requiring knowledge of or any modifications on the underlying network code. In addition, the scheme can be easily combined with a rank-metric-based error control scheme to provide both security and reliability.

Network coding has emerged as a new paradigm for communication in networks, allowing packets to be algebraically combined at internal nodes, rather than simply routed or replicated. The very nature of packet-mixing, however, makes the system highly sensitive to error propagation. Classical error correction approaches are therefore insufficient to solve the problem, which calls for novel techniques and insights. The main portion of this work is devoted to the problem of error control assuming an adversarial or worst-case error model. We start by proposing a general coding theory for adversarial channels, whose aim is to characterize the correction capability of a code. We then specialize this theory to the cases of coherent and noncoherent network coding. For coherent network coding, we show that the correction capability is given by the rank metric, while for noncoherent network coding, it is given by a new metric, called the injection metric. For both cases, optimal or near-optimal coding schemes are proposed based on rank-metric codes. In addition, we show how existing decoding algorithms for rank-metric codes can be conveniently adapted to work over a network coding channel. We also present several speed improvements that make these algorithms the fastest known to date. The second part of this work investigates a probabilistic error model. Upper and lower bounds on capacity are obtained for any channel parameters, and asymptotic expressions are provided in the limit of long packet length and/or large field size. A simple coding scheme is presented that achieves capacity in both limiting cases. The scheme has fairly low decoding complexity and a probability of failure that decreases exponentially both in the packet length and in the field size in bits. Extensions of the scheme are provided for several variations of the channel. A final contribution of this work is to apply rank-metric codes to a closely related problem: securing a network coding system against an eavesdropper. We show that the maximum possible rate can be achieved with a coset coding scheme based on rank-metric codes. Unlike previous schemes, our scheme has the distinctive property of being universal: it can be applied on top of any communication network without requiring knowledge of or any modifications on the underlying network code. In addition, the scheme can be easily combined with a rank-metric-based error control scheme to provide both security and reliability.

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Reference is the relation held to obtain between an expression and what a speaker or thinker intends the expression to represent. Reference is a component of interpretation, the process of giving terms, sentences, and thoughts semantic content. An example of reference in a formal context involves the natural numbers, where each one can be taken to have a corresponding set-theoretic counterpart as its referent. In an informal context reference is exemplified by the relation between a name and the specific name-bearer when a speaker or thinker utters or has the name in mind. Recent debates over reference have concerned the mechanism of reference: How is it that we can refer? In informal contexts, externalists see the reference relation as explicable in terms of the salient causal relations involved in the naming of a thing, or a class of things, and the ensuing causal chains leading to a term’s use. Opponents of this view—internalists—see the reference relation as being conceptually direct, and they take the external approach to rely on untenable metaphysical assumptions about the world’s structure. Moreover, some internalists take the permutability—i.e. the consistent reinterpretation—of certain referential schemes to confound the externalist picture of reference. In this thesis I focus on the reference of theoretical terms in science, and I argue for an externalist treatment of natural kinds and other theoretical elements. Along the way I offer a defense of the externalist’s pre-theoretic metaphysical assumptions and emphasize their central role in the interpretation of scientific languages. The externalist approach acknowledges the necessary constraints on reference-fixing that account for the schemes we employ, and this, I argue, confounds the permutation strategy.

Reference is the relation held to obtain between an expression and what a speaker or thinker intends the expression to represent. Reference is a component of interpretation, the process of giving terms, sentences, and thoughts semantic content. An example of reference in a formal context involves the natural numbers, where each one can be taken to have a corresponding set-theoretic counterpart as its referent. In an informal context reference is exemplified by the relation between a name and the specific name-bearer when a speaker or thinker utters or has the name in mind. Recent debates over reference have concerned the mechanism of reference: How is it that we can refer? In informal contexts, externalists see the reference relation as explicable in terms of the salient causal relations involved in the naming of a thing, or a class of things, and the ensuing causal chains leading to a term’s use. Opponents of this view—internalists—see the reference relation as being conceptually direct, and they take the external approach to rely on untenable metaphysical assumptions about the world’s structure. Moreover, some internalists take the permutability—i.e. the consistent reinterpretation—of certain referential schemes to confound the externalist picture of reference. In this thesis I focus on the reference of theoretical terms in science, and I argue for an externalist treatment of natural kinds and other theoretical elements. Along the way I offer a defense of the externalist’s pre-theoretic metaphysical assumptions and emphasize their central role in the interpretation of scientific languages. The externalist approach acknowledges the necessary constraints on reference-fixing that account for the schemes we employ, and this, I argue, confounds the permutation strategy.

This thesis focuses on decentralized deadbeat output regulation of discrete-time nonlinear plants that are composed of multiple agents. These agents interact, via scalar-valued signals, in a known structured way represented with a graph. This work is motivated by applications where it is infeasible and/or undesirable to introduce control action within each plant agent; instead, control agents are introduced to interact with certain plant agents, where each control agent focuses on regulating a specific plant agent, called its target. Then, two analyses are carried out to determine if regulation is achieved: targeting analysis is used to determine if control laws can be found to regulate all target agents, then growing analysis is used to determine the effect of those control laws on non-target plant agents. The strength of this novel approach is the intuitively-appealing notion of each control agent focusing on the regulation of just one plant agent. This work goes beyond previous research by generalizing the class of allowable plant dynamics, considering not only arbitrary propagation times through plant agents, but also allowing for non-symmetrical influence between the agents. Moreover, new necessary and sufficient algebraic conditions are derived to determine when targeting succeeds. The main contribution of this work, however, is the development of new easily-verifiable conditions necessary for targeting and/or growing to succeed. These new conditions are valuable due to their simplicity and scalability to large systems. They concern the positioning of control agents and targets as well as the propagation time of signals through the plant, and they help significantly with design decisions. Various graph structures (such as queues, grids, spiders, rings, etc.) are considered and for each, these conditions are used to develop a control scheme with the minimum number of control agents needed.

Risk attitudes are important for human decision making, especially in scenarios where huge wins or losses are possible, as exemplified by planetary rover navigation, oilspill response, and business applications. Decision-theoretic planners therefore need to take risk aspects into account to serve their users better. However, most existing decision-theoretic planners use simplistic planning objectives that are risk-neutral. The thesis research is the first comprehensive study of how to incorporate risk attitudes into decision-theoretic planners and solve large-scale planning problems represented as Markov decision process models. The thesis consists of three parts. The first part of the thesis work studies risk-sensitive planning in case where exponential utility functions are used to model risk attitudes. I show that existing decision-theoretic planners can be transformed to take risk attitudes into account. Moreover, different versions of the transformation are needed if the transition probabilities are implicitly given, namely, temporally extended probabilities and probabilities given in a factored form. The second part of the thesis work studies risk-sensitive planning in case where general nonlinear utility functions are used to model risk attitudes. I show that a state-augmentation approach can be used to reduce a risk-sensitive planning problem to a risk-neutral planning problem with an augmented state space. I further use a functional interpretation of value functions and approximation methods to solve the planning problems efficiently with value iteration. I also show an exact method for solving risk-sensitive planning problems where one-switch utility functions are used to model risk attitudes. The third part of the thesis work studies risk sensitive planning in case where arbitrary rewards are used. I propose a spectrum of conditions that can be used to constrain the utility function and the planning problem so that the optimal expected utilities exist and are finite. I prove that the existence and finiteness properties hold for stationary plans, where the action to perform in each state does not change over time, under different sets of conditions.

In this dissertation, two questions concerning monetary policy under the Taylor rule have been addressed. The first question is on, under the Taylor rule, whether a central bank should be responsible for both bank supervision and monetary policy or whether the two tasks should be exercised by separate institutions. This is the main focus of Chapter I. The second question is on whether the Taylor rule plays an important role in explaining modern business cycles in the United States. The second question has been covered by Chapter II. The implications of the first chapter can be summarized as follows: (i) it is inevitable for the central bank to have a systematic error in conducting monetary policy when the central bank does not have a bank supervisory role; (ii) without a bank supervisory role, the effectiveness of monetary policy cannot be guaranteed; (iii) because of the existence of conflict of interests, giving a bank supervisory role to the central bank does not guarantee the effectiveness of monetary policy, either; (iv) the way of setting up another government agency, bank regulator, and making the central bank and the regulator cooperate each other does not guarantee the effectiveness of monetary policy because, in this way, the systematic error in conducting monetary policy cannot be eliminated; (v) in the view of social welfare, not in the view of the effectiveness of monetary policy, it is better for the central bank to keep the whole responsibility or at least a partial responsibility on bank supervision. In the second chapter, we examined the effect of a technology shock and a money shock in the context of an RBC model incorporating the Taylor rule as the Fed??s monetary policy. One thing significantly different from other researches on this topic is the way the Taylor rule is introduced in the model. In this chapter, the Taylor rule is introduced by considering the relationship among the Fisher equation, Euler equation and the Taylor rule explicitly in the dynamic system of the relevant RBC model. With this approach, it has been shown that, even in a flexible-price environment, the two major failures in RBC models with money can be resolved. Under the Taylor rule, the correlation between output and inflation appears to be positive and the response of our model economy to a shock is persistent. Furthermore, the possibility of an existing liquidity effect is found. These results imply that the Taylor rule does play a key role in explaining business cycles in the United States.