Players with Limited Memory

This paper studies a model of memory. The model takes into account that memory capacity is limited and imperfect. We study how agents with such memory limitations, who have very little information about their choice environment, play games. In particular, the players do not know if they are playing a game. We show that players do better in games than in decision problems. This is because the players, unknowingly, improve the environment they face in games. We also show that people can do quite well in games even with severely limited memories, although memory restrictions tend to make them behave cautiously. Lastly, we introduce a solution concept approiate for analysis games in which the players may have limited knowledge of their environment and have some memory restictions. We show hos this solution concept is related to other like the iterated removal of strictly dominated strategies.

Forgetting to Remember: From Benjamin to Blanchot

Let us begin with Lethe, a river in Hades whose waters caused forgetfulness to dead souls who drank from it. The daughter of Eris, Lethe was the sister of Thanatos , and with Zeus she bore the Graces/Charites. According to some myths, she was the mother of Dionysus. She was the goddess of oblivion and the river with the same name. When someone died and went to Hades, they had to drink from her water so they would forget their previous existence on earth. Once they had drunk from the waters of Lethe, they were left with nothing to reminisce about for eternity. If ever anybody was allowed back to life, again they had to drink from the river so they would not remember the afterlife. One of memorys earliest myths proclaims that at the dawn of philosophy, at the oracle of Lebadeia, a descent into Hades required that the questor be first taken to Lethe, the spring of forgetfulness, and then to Mnemosyne, the mother of the Muses, the second spring, the spring of remembrance. Jean Pierre Vernant recounts the legend thus: Before venturing into the mouth of hell, the questor, who had already undergone rites of purification, was taken to two springs named respectively Lethe and Mnemosoune. He drank from the first and immediately forgot everything to do with his human life and, like a dead man, he entered the realm of Night. The water of the second spring was to enable him to remember all that he had seen and heard in the other world. When he returned he was no longer restricted to knowledge of the present moment: contact with the beyond had revealed both past and future to him. 2 Two questions that immediately come to mind are concerned with the anteriority of forgetting in relation to memory. Why was the initiate taken first to Lethe? What was the motivation behind this unusual ritual in the cavern of Trophonius in Boetia that demands forgetfulness as the first step? Secondly, why is the power of memory, which enables him to remember what he had seen and heard in the other world, constituted as the second step though unmistakably a step, an unmistakable step toward knowledge? The dip in the Lethe cleanses the initiate from the distracting and unmitigated sorrows of the past like a clean slate. It is well known that for the ancient Greeks, knowledge, a source of immortality, derived from memory. One could ask, is the knowledge that memory brings to us the knowledge that memory is the first presence of what was before it, namely forgetting

Private Functional Encryption – Hiding What Cannot Be Learned Through Function Evaluation

Functional encryption (FE) is a generalization of many commonly employed crypto- graphic primitives, such as keyword search encryption (KS), identity-based encryption (IBE), inner-product encryption (IPE) and attribute-based encryption (ABE). In an FE scheme, the holder of a master secret key can issue tokens associated with functions of its choice. Possessing a token for f allows one to recover f(m), given an encryption of m. As it is important that ciphertexts preserve data privacy, in various scenarios it is also important that tokens do not expose their associated function. A notable example being the usage of FE to search over encrypted data without revealing the search query. Function privacy is an emerging new notion that aims to address this problem. The difficulty of formalizing it lies in the verification functionality, as the holder of a token for function f may encrypt arbitrary messages using the public key, and obtain a large number of evaluations of f. Prior privacy models in the literature were fine-tuned for specific functionalities, did not model correlations between ciphertexts and decryption tokens, or fell under strong uninstantiability results. Our first contribution is a new indistinguishability-based privacy notion that overcomes these limitations and is flexible enough to capture all previously proposed indistinguishability-based definitions as particular cases. The second contribution of this thesis is five constructions of private functional encryption supporting different classes of functions and meeting varying degrees of security: (1) a white-box construction of an Anonymous IBE scheme based on composite-order groups, shown to be secure in the absence of correlated messages; (2) a simple and functionality- agnostic black-box construction from obfuscation, also shown to be secure in the absence of correlated messages; (3) a more evolved and still functionality-agnostic construction that achieves a form of function privacy that tolerates limited correlations between messages and functions; (4) a KS scheme achieving privacy in the presence of correlated messages beyond all previously proposed indistinguishability-based security definitions; (5) a KS construction that achieves our strongest notion of privacy (but relies on a more expressive form of obfuscation than the previous construction). The standard approach in FE is to model complex functions as circuits, which yields inefficient evaluations over large inputs. As our third contribution, we propose a new primitive that we call “updatable functional encryption” (UFE), where instead of circuits we deal with RAM programs, which are closer to how programs are expressed in von Neumann architecture. We impose strict efficiency constrains and we envision tokens that are capable of updating the ciphertext, over which other tokens can be subsequently executed. We define a security notion for our primitive and propose a candidate construction from obfuscation, which serves as a starting point towards the realization of other schemes and contributes to the study on how to compute RAM programs over public-key encrypted data

Symbolic Equation Solving via Reinforcement Learning

Machine-learning methods are gradually being adopted in a great variety of social, economic, and scientific contexts, yet they are notorious for struggling with exact mathematics. A typical example is computer algebra, which includes tasks like simplifying mathematical terms, calculating formal derivatives, or finding exact solutions of algebraic equations. Traditional software packages for these purposes are commonly based on a huge database of rules for how a specific operation (e.g., differentiation) transforms a certain term (e.g., sine function) into another one (e.g., cosine function). Thus far, these rules have usually needed to be discovered and subsequently programmed by humans. Focusing on the paradigmatic example of solving linear equations in symbolic form, we demonstrate how the process of finding elementary transformation rules and step-by-step solutions can be automated using reinforcement learning with deep neural networks.Comment: 12 pages, 4 figures + appendices 17 pages, 1 figure, 16 table

The development of a work instability scale for multiple sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system leading to progressive impairment of various neurological functions (Kesslering et al, 2002). It is the commonest cause of chronic neurological disability among young adults in the western world (Me Donnell et al, 2001). The physical and psychological effects of multiple sclerosis can impact heavily on any of these important life activities and so people with multiple sclerosis are more likely to be unemployed than the general population (Solari et al, 2001). Premature unemployment can have significant financial and social consequences in adulthood. Like the majority of the general population, many of those who have multiple sclerosis will still have dependants and regular financial commitments in their forties and fifties, such as a mortgage. Therefore, unemployment may be disastrous for the family, especially if it is the main wage earner who loses their job. Background: As well as the financial gain from work, it can also be an enjoyable activity that can define people and help them fulfil a social role. In recent years there has been more awareness of the burden of disease, not just physically but emotionally and financially and the disease and demographic factors contributing to job loss in the multiple sclerosis population have been identified. The effect of vocational rehabilitation in chronic diseases has also been explored to a degree and the Organisation for Economic Co-operation and Development (OECD) report in 2003 stated that early vocational rehabilitation intervention is the most effective measure against the dependence on benefits that is a consequence of long-term ill health (Frank, 2003). However at present there is no outcome measure to assess the need for intervention and it still remains to be seen if costly interventions, such as, the disease modifying therapies or vocational rehabilitation have any effect on the working life of those with multiple sclerosis. Work disability is premature work cessation due to a health problem or disability. Prior to work disability there may be a period of work instability. Work instability is a state in which the consequences of a mismatch between an individual’s functional abilities and the demands of his or her job can threaten continuing employment if not resolved. During this time the patient is most at risk of job loss and timely intervention in the work place can facilitate job retention (Gilworth et al, 2003).The aim of this thesis was to produce a valid and reliable Work Instability Scale (WIS) for multiple sclerosis in order to be able to predict those at risk of job loss. Methods: A multiple methodological approach, involving both qualitative and quantitative research techniques was used and a disease specific, work instability scale, the MS-WIS was developed and tested for appropriate psychometric properties. In depth, semi-structured interviews were conducted with people with MS in order to explore the issues of working while having MS. Qualitative analysis of these interviews using a grounded theory approach yielded themes that described the issues of working with MS. Further qualitative analysis of the interviews using content analysis methodology was being done alongside this which identified the items suitable for inclusion in the scale, a process known as item generation. The scale was then subjected to in-depth psychometric testing using Rasch analysis. Rasch analysis was chosen as this would ensure that a single construct was being measured and allowed the validity and the reliability of the scale to be tested. Results: Twenty seven people were interviewed for the qualitative study, fifteen men and twelve women and the interviews transcribed and studied. Four main themes emerged as factors contributing to work instability on qualitative analysis of the data: i) The impact upon work of the physical and cognitive aspects of the disease. ii) The extent to which the environment and organisational aspects of working life can affect job ability and retention. iii) The social aspects of the working environment. iv) The psychological aspects of working. Item generation initially yielded a scale consisting of one hundred and twenty two items. A postal questionnaire yielded 109 responses, the data from which then had to undergo in-depth Rasch analysis, during which items were discarded. Vocational assessment was used as a gold standard. This process resulted in a valid, reliable twenty one item scale - the Multiple Sclerosis Work Instability Scale (MS - WIS). The final scale is quick and easy to complete. It is scored in 3 bands indicating low, medium and high risk of Work Disability. The medium - risk threshold has 88% sensitivity and 60% specificity and the sensitivity and specificity of the scale reaches 100% at the high - risk threshold with regards to the need for work place intervention. Conclusion: MS has been shown to have a considerable impact on the working life of the individual. A disease specific outcome measure to quantify the risk of job loss in an individual with MS with good psychometric properties has been developed. The MS-WIS has been derived from a strong conceptual framework and a strong mathematical measurement model. It has been rigorously tested for its psychometric properties and has high sensitivity and specificity for risk of job loss

How do the attitudes and beliefs of healthcare professionals and older people impact on the appropriate use of multi-compartment compliance aids by older people living at home

Compliance with medication regimes is a widely researched topic within the field of healthcare. Older people are considered to be a greater risk of non-compliance due to multiple morbidities. Multi-compartment compliance aids are frequently issued to older people in an attempt to improve their medicines management. This thesis aims to determine whether the attitudes and beliefs of both the older people who use MCAs and the healthcare professionals who request their use, influence the use of such devices by older people living in the community. A preliminary study which investigated the use of MCAs in primary care is described. The findings suggested that over 100,00 people in the UK may be issued with a MCA despite little evidence for their efficacy. The literature review undertaken for this thesis concludes that very few studies have been undertaken in this area and those which have are mainly of poor quality. The results from these studies failed to conclusively support the use of these devices and further rigorous conducted studies are needed. The main study comprises qualitative, in-depth semi-structured interviews with older people, who are using a MCA and healthcare professionals. The interviews were analysed using a grounded theory approach. The study revealed that older people find MCAs easy to use and convenient although a minority of the participants did experience difficulties using the device. Maintaining independence and remaining in control was important for all the older people and this influenced their attitudes towards using their MCA. The healthcare professionals concurred with the observation that MCAs were convenient to use and despite a minority stating that MCAs assisted older people to remember to take their medication, the majority acknowledged that this was not the case. The healthcare professionals agreed that the decision to issue a MCA could be seen as paternalistic however there remained a belief that the issue of a MCA would assist the older person take their medication correctly. The thesis concludes by providing details of a proposed method for undertaking a holistic, patient-centred, multi-disciplinary assessment of older people's medicines management abilities

The function of ethical judgments in impression formation

Thesis (M.A.)--University of Kansas, Speech Communication and Human Relations, 1980

Classical noise in quantum systems.

Ph. D. University of KwaZulu-Natal, Durban, 2013.Quantum mechanics contains a fresh and mysterious view of reality. Besides the philosophical intrigue, it has also produced and continues to inspire tantalizing new technological innovations. In any technological system, the designers must contend with the problem of noise. This thesis studies classical noise in two different quantum settings. The first is the classical capacity of a quantum channel with memory. Adding forgetful-memory, attempts to push the boundaries of our understanding of how best to transmit information in the presence of correlated noise. We study the noise within two different frameworks; Algebraic Measure theory and Monte Carlo simulations. Both tools are used to calculate the capacity of the channel as correlations in the noise are increased. The second classical-quantum system investigated is atomic clocks. Using power spectral density methods we study aliasing noise induced by periodic-correction which includes the Dick Effect. We propose a novel multi-window scheme that extends the standard method of noise correction and exhibits better anti-aliasing properties. A uniting thread that emerges is that correlations can be put to good use. In the classical capacity setting, correlations occur between uses of the quantum channel. We show that stronger correlations increase the classical capacity. The benefits of correlation are even seen at a meta-level within the framework of Monte Carlo simulations. Correlations are designed into the algorithm which have nothing to do with real-world correlations, but are abstract correlations created by a Markov chain employed in the algorithm to help efficiently sample from a distribution of exponential size. Finally, in the atomic clock setting, correlations in the measured noise are used to help predict and cancel noise on a short time-scale while trying to limit aliasing. Channel capacity and precise time-keeping are distinct topics and require very different approaches to study. However, common to both topics is their application to com- munication and other tasks, the need to overcome noise and the benefits of exploiting correlations in the noise

Quantum information processing with Clifford quantum cellular automata

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