SOFTWARE DIAGNOSIS USING COMPRESSED SIGNATURE SEQUENCES

Software monitoring and debugging can be efficiently supported by one of the concurrent error detection methods, the application of watchdog processors. A watchdog processor, as a co-processor, receives and evaluates signatures assigned to the states of the program execution. After the checking, it stores the run-time sequence of signatures which identify the statements of the program. In this way, a trace of the statements executed before the error is available. The signature buffer can be efficiently utilized if the signature sequence is compressed. In the paper, two real-time compression methods are presented and compared. The first one uses predefined dictionaries, while the other one utilizes the structural information encoded in the signatures

Szeged lesz, és szebb lesz, mint volt : a szegedi kisajátítás jogintézménye (1879-1884)

The implementation of the Szeged expropriation law is one of the somewhat neglected areas of the former research, so the core of my work was provided by archival materials. Unfortunately many of these were lost, due to the two world wars and the fact that most of the documents of the Szeged Royal Commission were transferred to Budapest. Within the expropriation, there were 2 forms of compensation: one was monetary compensation, which was paid from the expropriation fund, and the other was the land exchange, which was observed in Szeged for the first time, therefore counted as a unique way at that time. In most of the cases the latter happened. There have been several examples where the value of the offered land was higher compared to the original land to be expropriated. In these cases the owner had to pay more to the extent of his enrichment, and the surplus of the money has gone into the expropriation fund. One of the most important moments in the process of expropriation was the publication of the plans. The persons concerned have been notified about the place and time of the auditions. There were cases when not everyone showed up. In those times the assigned case manager represented them. Sometimes they also announced supplementary dates as well. During the process of expropriation, a tendency can be observed: at first they have tried to get those privately owned plots, where they have planned to build public administration buildings, such as the one what is currently functioning as the main building of the Faculty of Law, but was originally meant to be a girls’ school. During the selection of the site, this goal was already in front of the members of the committee. After the expropriation, the land became the property of the Expropriation Committee, and then it was given to the city of Szeged on the condition that the school must be built there. The land block arrangements also started in this period, around the Móra, Csendes and Szivárvány streets, where there were 5 cases of land exchange. In four out of these five cases, the owners had to pay the difference because the new plots were worth more than the original plots. The arrangement of modern boulevards and boulevards required the expropriation of many privately owned land. One of the best-known examples of this was the case of Simon Grösser. He opposed expropriation and did everything he could to prevent it. There were many houses near the upper shore of the river Tisza, which have remained in good conditions after the flood, and this was one of the main reasons for Simon Grösser’s repeated appeals. If his house remained in good condition, then why is the expropriation necessary. The same thing happened in several parts of the city, and in these cases the old image of the city has remained in its original form. Residents of Szeged and visitors know the Kárász street and its surroundings as the old town. The reason is this is the point where a larger cluster of pre-flood buildings have been preserved, but these have also been built in the 19th century. In fact, the really old part of the city is the area now known as the Upper Town, which was already inhabited in the Middle Ages. Medieval foundations can still be observed in the basements of some houses in the mentioned district of the city. As a conclusion we can say that during the reconstruction of the city, two very important aspects had to be considered: one is to keep the river away from the city and the other is to raise the level of the city. Tenders were issued for both processes, which were both won by Guilbard Gregerson. The extraction of large quantities of soil has became possible also by expropriation. The surrounding lands, such as Szentmihálytelek, Szőreg and Öthalom have been used as soil mines for the building of the embankments and for the raising of the level of the reconstructed Szeged

Constraint Programming with Multi-valued Decision Diagrams: A Saturation Approach

Constraint programming is a declarative way of modeling and solving optimization and satisfiability problems over finite domains. Traditional solvers use search-based strategies enhanced with various optimizations to reduce the search space. One of such techniques involves multi-valued decision diagrams (MDD) to maintain a superset of potential solutions, gradually discarding combinations of values that fail to satisfy some constraint. Instead of the relaxed MDDs representing a superset, we propose to use exact MDDs to compute the set of solutions directly without search, compactly encoding all the solutions instead of enumerating them. Our solution relies on the main idea of the saturation algorithm used in model checking to reduce the required computational cost. Preliminary results show that this strategy can keep the size of intermediate MDDs small during the computation

PROGRAM CODE GENERATION BASED ON UML STATECHART MODELS

Since visual modelling languages are getting more and more popular, the automatic generation of the program code on the basis of high-level models is an important issue. This article discusses implementation possibilities of statecharts, the graphical notation for describing state-based event-driven behaviour in the Unified Modelling Language (UML). The first part of the article outlines common approaches published in the literature and identifies their weaknesses. In the second part an implementation pattern is proposed that is capable of efficiently instantiating most of the statechart features. The pattern developed by us poses low hardware requirements therefore applicable even in embedded systems

CONTROL FLOW CHECKING IN MULTITASKING SYSTEMS

The control flow checking technique presented in our paper is based on the new watchdog- processor method SEIS1 (Signature Encoded Instruction Stream). This method is in- tended to check the still uncovered area of state-of-the-art microprocessors using on-chip caches or instruction pipelines, since the processor instruction bus needs not be monitored. The control flow is checked using assigned actual signatures and embedded reference sig- natures. Since the actual and reference signatures are embedded in the checked program, the usual reference database and the time-consuming search/ compare engine in the watch- dog can be omitted. The evaluation of the actual signature is a simple combinatorial task allowing high speed and thus the sharing of the watchdog between different tasks and processors. The checking method has been extended to higher levels of the application like simultaneous check of different processes and their synchronization in multitasking systems

Aspect-oriented modelling and analysis of information systems

In this paper we introduce an approach of aspect-oriented modelling and analysis of information systems. First we give an overview of the concepts of Aspect Oriented Programming and provide an outlook to model aspect-oriented programs. On the basis of this introduction, we describe a method of using aspects at the modelling level and weaving them into a single integrated model. Finally, we extend this framework with the automatic construction of analysis models based on separate aspect models. In our example, fault tolerance structures are modelled by aspects and the analysis model is a dependability model that is used to determine the non-functional properties of the system like reliability and availability. In this way the separate design of the functionality and the dependability is supported and the design decisions concerning fault tolerance can be analysed on the basis of the dependability model