Imaging Evil in the First Chapters of Genesis: Texts behind the Images in Eastern Orthodox Art

Satan’s interference in the events described in the first chapters of the book of Genesis and in the life of the protoplasts is not mentioned at all in the biblical text. This happens, however, in pseudo-canonical texts. The article is a short survey on the apocryphal accounts that mention Satan and their influence on art. The main focus is put on the inclusion of the image of Satan behind Cain’s figure in a number of depictions of the scene The Murder of Abel in the Russian art of the 16th and 17th centuries. The possible links between this visual motif with several literary sources is examined, among them the Short and the Explanatory Palaea, the Tale of Bygone Years (Povest’ vremennykh let or Primary Chronicle), Russian recensions of the apocryphon The Sea of Tiberias, and of The Revelation of Pseudo-Methodius of Patara. In addition, some instances of the same visual decision in Balkan art are pointed out and their connection to Russian models is underlined

Adaptive workflow nets for grid computing

Existing grid applications commonly use workflows for the orchestration of grid services. Existing workflow models however suffer from the lack of adaptivity. In this paper we define Adaptive Grid Workflow nets (AGWF nets) appropriate for modeling grid workflows and allowing changes in the process structure as a response to triggering events/exceptions. Moreover, a recursion is allowed, which makes the model especially appropriate for a number of grid applications. We show that soundness can be verified for AGWF nets

Adaptive Workflow Nets for Grid Computing

Abstract. Existing grid applications commonly use workflows for the orchestration of grid services. Existing workflow models however suf-fer from the lack of adaptivity. In this paper we define Adaptive Grid Workflow nets (AGWF nets) appropriate for modeling grid workflows and allowing changes in the process structure as a response to trigger-ing events/exceptions. Moreover, a recursion is allowed, which makes the model especially appropriate for a number of grid applications. We show that soundness can be verified for AGWF nets

Parallel implementation of italiano's incremental algorithm for dynamic updating the transitive closure

The transitive closure (or reachability) problem in a directed graph consists in finding whether there is a path between any two vertices. In this paper, we first study the problem of parallelization of Italiano's algorithm for dynamic updating the transitive closure after inserting a new arc into the graph represented as a list of arcs. To this end, by means of the data structure first proposed in [9], Italiano's incremental algorithm is represented in a natural way on a model of an associative parallel processor with vertical processing (the STAR-machine). Associative version of Italiano's incremental algorithm is given as procedure InsertArc for the STAR-machine. We prove correctness of this procedure and evaluate its time complexity. We also compare implementations of Italiano's incremental algorithm and its associative version and present the main advantages of the associative version.Проблема транзитивного замыкания (или достижимости) в ориентированном графе состоит в определении того, существует ли путь между любыми двумя вершинами. В данной статье впервые исследуется задача параллельной реализации алгоритма Итальяно для динамической обработки транзитивного замыкания после добавления к графу новой дуги для случая, когда граф задается в виде списка дуг. С этой целью с помощью структуры данных, впервые предложенной в работе [9], инкрементальный алгоритм Итальяно естественным образом представляется на модели ассоциативного параллельного процессора с вертикальной обработкой данных (STAR- машине). Ассоциативная версия инкрементального алгоритма Итальяно задается в виде процедуры InsertArc для STAR- машины. Доказывается корректность этой процедуры и оценивается ее временная сложность. Также проводится сравнение выполнения инкрементального алгоритма Итальяно и его ассоциативной версии и приводятся основные преимущества ассоциативной версии

О разрешимости бездефектности для сетей потоков работ с неограниченным ресурсом

In this work, we consider the modeling of workflow systems with Petri nets. A resource workflow net (RWF-net) is a workflow net supplied with an additional set of initially marked resource places. Resources can be consumed and/or produced by transitions. We constrain neither the intermediate nor final resource markings, hence a net can have an infinite number of different reachable states. An initially marked RWF-net is called sound if it properly terminates its work and, moreover, an increase of the initial resource does not violate its proper termination. An unmarked RWF-net is sound if it is sound for some initial resource. In this paper, we prove the decidability of both marked and unmarked soundness for a restricted class of RWF-nets with a single unbounded resource place (1-dim RWF-nets). We present an algorithm for computing the minimal sound resource for a given sound 1-dim RWF-net.Рассматривается моделирование схем потоков работ (workflow) при помощи сетей Петри. Определяется класс сетей потоков работ с ресурсами (RWF- сетей) — обычных workflow-сетей, в которых дополнительно добавлено множество ресурсных позиций, содержащих какую-то начальную разметку (начальный ресурс). Ресурсы могут уничтожаться и производиться при срабатываниях переходов. Мы не накладываем ограничений ни на промежуточные, ни на финальные ресурсные разметки, поэтому сеть может порождать бесконечное множество различных достижимых состояний. RWF-сеть с данной начальной ресурсной разметкой называется бездефектной, если, во-первых, она всегда корректно завершает свою работу, и, во- вторых, любое увеличение начального ресурса не нарушает свойства корректного завершения. Неразмеченная RWF-сеть бездефектна, если она бездефектна при некоторой начальной ресурсной разметке. В данной работе доказана разрешимость обоих вариантов бездефектности для важного подкласса RWF- сетей — сетей с одномерным ресурсом (одной ресурсной позицией). Также представлен алгоритм вычисления наименьшего бездефектного ресурса

Compiler assisted chekpointing of message-passing applications in heterogeneous environments

[Resumen] With the evolution of high performance computing towards heterogeneous, massively parallel systems, parallel applications have developed new checkpoint and restart necessities, Whether due to a failure in the execution or to a migration of the processes to different machines, checkpointing tools must be able to operate in heterogeneous environments. However, some of the data manipulated by a parallel application are not truly portable. Examples of these include opaque state (e.g. data structures for communications support) or diversity of interfaces for a single feature (e.g. communications, I/O). Directly manipulating the underlying ad-hoc representations renders checkpointing tools incapable of working on different environments. Portable checkpointers usually work around portability issues at the cost of transparency: the user must provide information such as what data needs to be stored, where to store it, or where to checkpoint. CPPC (ComPiler for Portable Checkpointing) is a checkpointing tool designed to feature both portability and transparency, while preserving the scalability of the executed applications. It is made up of a library and a compiler. The CPPC library contains routines for variable level checkpointing, using portable code and protocols. The CPPC compiler achieves transparency by relieving the user from time-consuming tasks, such as performing code analyses and adding instrumentation code

Contributions on agreement in dynamic distributed systems

139 p.This Ph.D. thesis studies the agreement problem in dynamic distributed systems by integrating both the classical fault-tolerance perspective and the more recent formalism based on evolving graphs. First, we developed a common framework that allows to analyze and compare models of dynamic distributed systems for eventual leader election. The framework extends a previous proposal by Baldoni et al. by including new dimensions and levels of dynamicity. Also, we extend the Time-Varying Graph (TVG) formalism by introducing the necessary timeliness assumptions and the minimal conditions to solve agreement problems. We provide a hierarchy of time-bounded, TVG-based, connectivity classes with increasingly stronger assumptions and specify an implementation of Terminating Reliable Broadcast for each class. Then we define an Omega failure detector, W, for the eventual leader election in dynamic distributed systems, together with a system model, , which is compatible with the timebounded TVG classes. We implement an algorithm that satisfy the properties of W in M. According to our common framework, M results to be weaker than the previous proposed dynamic distributed system models for eventual leader election. Additionally we use simulations to illustrate this fact and show that our leader election algorithm tolerates more general (i.e., dynamic) behaviors, and hence it is of application in a wider range of practical scenarios at the cost of a moderate overhead on stabilization times

Distributed eventual leader election in the crash-recovery and general omission failure models.

102 p.Distributed applications are present in many aspects of everyday life. Banking, healthcare or transportation are examples of such applications. These applications are built on top of distributed systems. Roughly speaking, a distributed system is composed of a set of processes that collaborate among them to achieve a common goal. When building such systems, designers have to cope with several issues, such as different synchrony assumptions and failure occurrence. Distributed systems must ensure that the delivered service is trustworthy.Agreement problems compose a fundamental class of problems in distributed systems. All agreement problems follow the same pattern: all processes must agree on some common decision. Most of the agreement problems can be considered as a particular instance of the Consensus problem. Hence, they can be solved by reduction to consensus. However, a fundamental impossibility result, namely (FLP), states that in an asynchronous distributed system it is impossible to achieve consensus deterministically when at least one process may fail. A way to circumvent this obstacle is by using unreliable failure detectors. A failure detector allows to encapsulate synchrony assumptions of the system, providing (possibly incorrect) information about process failures. A particular failure detector, called Omega, has been shown to be the weakest failure detector for solving consensus with a majority of correct processes. Informally, Omega lies on providing an eventual leader election mechanism