951 resultados para Symbolic tokens
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We have been investigating the cryptographical properties of in nite families of simple graphs of large girth with the special colouring of vertices during the last 10 years. Such families can be used for the development of cryptographical algorithms (on symmetric or public key modes) and turbocodes in error correction theory. Only few families of simple graphs of large unbounded girth and arbitrarily large degree are known. The paper is devoted to the more general theory of directed graphs of large girth and their cryptographical applications. It contains new explicit algebraic constructions of in finite families of such graphs. We show that they can be used for the implementation of secure and very fast symmetric encryption algorithms. The symbolic computations technique allow us to create a public key mode for the encryption scheme based on algebraic graphs.
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The paper has been presented at the 12th International Conference on Applications of Computer Algebra, Varna, Bulgaria, June, 2006
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We discuss some main points of computer-assisted proofs based on reliable numerical computations. Such so-called self-validating numerical methods in combination with exact symbolic manipulations result in very powerful mathematical software tools. These tools allow proving mathematical statements (existence of a fixed point, of a solution of an ODE, of a zero of a continuous function, of a global minimum within a given range, etc.) using a digital computer. To validate the assertions of the underlying theorems fast finite precision arithmetic is used. The results are absolutely rigorous. To demonstrate the power of reliable symbolic-numeric computations we investigate in some details the verification of very long periodic orbits of chaotic dynamical systems. The verification is done directly in Maple, e.g. using the Maple Power Tool intpakX or, more efficiently, using the C++ class library C-XSC.
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An algorithm is produced for the symbolic solving of systems of partial differential equations by means of multivariate Laplace–Carson transform. A system of K equations with M as the greatest order of partial derivatives and right-hand parts of a special type is considered. Initial conditions are input. As a result of a Laplace–Carson transform of the system according to initial condition we obtain an algebraic system of equations. A method to obtain compatibility conditions is discussed.
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ACM Computing Classification System (1998): G.1.1, G.1.2.
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2000 Mathematics Subject Classification: 13N15, 13A50, 13F20.
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This study examined contextual and situational influences on older adults' decision to complete advance directives by means of a conceptual framework derived from symbolic interactionist theory and a cross-sectional, correlational research design. It was hypothesized that completion of advance directives among older adults would be associated with visiting or participating in the care of a terminally ill or permanently incompetent individual sustained by technology. Using a 53-item questionnaire, computer assisted telephone interviews (CATI) were conducted with 398 community dwelling adults between September and October 2003. Respondents were contacted using random-select dialing from a listed sample of 99% of household telephone numbers in one South Florida census tract. Over 90% of households in this tract include an individual age 65 or older. ^ The results revealed that contrary to most reports in the literature a substantial proportion of older adults (82%) had completed advance directives and that the link between older adults and document completion was mainly through attorneys and not mandated agents, health care professionals. Further, more than one third of older adults reported that religion/spirituality was not an important part of their life, suggesting that the recommended practice of offering religious/spiritual counseling to all those approaching death be reexamined. The hypothesis was not supported (p > .05) and is explained by the situational emphasis on the variables rather than on structural influences. In logistic regression analysis, only increasing age (p = .001) and higher education (p = < .001) were significant but explained only 10% of the variance in document completion. ^ Based on the findings, increased interdisciplinary collaboration is suggested with regard to the advance directive agenda. Since attorneys play a key role in document completion, other professions should seek their expertise and collaboration. In addition, the inclusion of a religious/spiritual preference section in all living wills should be considered as an essential part of a holistic and individually appropriate document. Implications for social work education, practice, and advocacy are discussed as well as suggestions for further research. ^
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The purpose of this research was to apply model checking by using a symbolic model checker on Predicate Transition Nets (PrT Nets). A PrT Net is a formal model of information flow which allows system properties to be modeled and analyzed. The aim of this thesis was to use the modeling and analysis power of PrT nets to provide a mechanism for the system model to be verified. Symbolic Model Verifier (SMV) was the model checker chosen in this thesis, and in order to verify the PrT net model of a system, it was translated to SMV input language. A software tool was implemented which translates the PrT Net into SMV language, hence enabling the process of model checking. The system includes two parts: the PrT net editor where the representation of a system can be edited, and the translator which converts the PrT net into an SMV program.
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Design embeds ideas in communication and artefacts in subtle and psychologically powerful ways. Sociologist Pierre Bourdieu coined the term ‘symbolic violence’ to describe how powerful ideologies, priorities, values and even sensibilities are constructed and reproduced through cultural institutions, processes and practices. Through symbolic violence, individuals learn to consider unjust conditions as natural and even come to value customs and ideas that are oppressive. Symbolic violence normalises structural violence and enables real violence to take place, often preceding it and later justifying it. Feminist, class, race and indigenous scholars and activists describe how oppressions (how patriarchy, racism, colonialism, etc.) exist within institutions and structures, and also within cultural practices that embed ideologies into everyday life. The theory of symbolic violence sheds light on how design can function to naturalise oppressions and then obfuscate power relations around this process. Through symbolic violence, design can function as an enabler for the exploitation of certain groups of people and the environment they (and ultimately ‘we’) depend on to live. Design functions as symbolic violence when it is involved with the creation and reproduction of ideas, practices, tools and processes that result in structural and other types of violence (including ecocide). Breaking symbolic violence involves discovering how it works and building capacities to challenge and transform dysfunctional ideologies, structures and institutions. This conversation will give participants an opportunity to discuss, critique and/or develop the theory of design as symbolic violence as a basis for the development of design strategies for social justice.
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This chapter presents an exploratory study involving a group of athletic shoe enthusiasts and their feelings towards customized footwear. These "sneakerheads" demonstrate their infatuation with sneakers via activities ranging from creating catalogs of custom shoes to buying and selling rare athletic footwear online. The key characteristic these individuals share is that, for them, athletic shoes are a fundamental fashion accessory stepped in symbolism and meaning. A series of in-depth interviews utilizing the Zaltman Metaphor Elicitation Technique (ZMET) provide a better understanding of how issues such as art, self-expression, exclusivity, peer recognition, and counterfeit goods interact with the mass customization of symbolic products by category experts.
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Symbolic execution is a powerful program analysis technique, but it is very challenging to apply to programs built using event-driven frameworks, such as Android. The main reason is that the framework code itself is too complex to symbolically execute. The standard solution is to manually create a framework model that is simpler and more amenable to symbolic execution. However, developing and maintaining such a model by hand is difficult and error-prone. We claim that we can leverage program synthesis to introduce a high-degree of automation to the process of framework modeling. To support this thesis, we present three pieces of work. First, we introduced SymDroid, a symbolic executor for Android. While Android apps are written in Java, they are compiled to Dalvik bytecode format. Instead of analyzing an app’s Java source, which may not be available, or decompiling from Dalvik back to Java, which requires significant engineering effort and introduces yet another source of potential bugs in an analysis, SymDroid works directly on Dalvik bytecode. Second, we introduced Pasket, a new system that takes a first step toward automatically generating Java framework models to support symbolic execution. Pasket takes as input the framework API and tutorial programs that exercise the framework. From these artifacts and Pasket's internal knowledge of design patterns, Pasket synthesizes an executable framework model by instantiating design patterns, such that the behavior of a synthesized model on the tutorial programs matches that of the original framework. Lastly, in order to scale program synthesis to framework models, we devised adaptive concretization, a novel program synthesis algorithm that combines the best of the two major synthesis strategies: symbolic search, i.e., using SAT or SMT solvers, and explicit search, e.g., stochastic enumeration of possible solutions. Adaptive concretization parallelizes multiple sub-synthesis problems by partially concretizing highly influential unknowns in the original synthesis problem. Thanks to adaptive concretization, Pasket can generate a large-scale model, e.g., thousands lines of code. In addition, we have used an Android model synthesized by Pasket and found that the model is sufficient to allow SymDroid to execute a range of apps.