Hardcoding and dynamic implementation of finite automata

The theoretical complexity of a string recognizer is linear to the length of the string being tested for acceptance. However, for some kind of strings the processing time largely depends on the number of states visited by the recognizer at run-time. Various experiments are conducted in order to compare the time efficiency of both hardcoded and table-driven algorithms when using such strings patterns. The results of the experiments are cross-compared in order to show the efficiency of the hardcoded algorithm over its table-driven counterpart. This help further the investigations on the problem of the dynamic implementation of finite automata. It is shown that we can rely on the history of the states previously visited in the dynamic framework in order to predict the suitable algorithm for acceptance testing

Hardcoding finite automata

Please read the abstract in the section 00front of this documentDissertation (MSc (Computer Science))--University of Pretoria, 2003.Computer Scienceunrestricte

Proceedings of the Eindhoven FASTAR Days 2004 : Eindhoven, The Netherlands, September 3-4, 2004

The Eindhoven FASTAR Days (EFD) 2004 were organized by the Software Construction group of the Department of Mathematics and Computer Science at the Technische Universiteit Eindhoven. On September 3rd and 4th 2004, over thirty participants|hailing from the Czech Republic, Finland, France, The Netherlands, Poland and South Africa|gathered at the Department to attend the EFD. The EFD were organized in connection with the research on finite automata by the FASTAR Research Group, which is centered in Eindhoven and at the University of Pretoria, South Africa. FASTAR (Finite Automata Systems|Theoretical and Applied Research) is an in- ternational research group that aims to lead in all areas related to finite state systems. The work in FASTAR includes both core and applied parts of this field. The EFD therefore focused on the field of finite automata, with an emphasis on practical aspects and applications. Eighteen presentations, mostly on subjects within this field, were given, by researchers as well as students from participating universities and industrial research facilities. This report contains the proceedings of the conference, in the form of papers for twelve of the presentations at the EFD. Most of them were initially reviewed and distributed as handouts during the EFD. After the EFD took place, the papers were revised for publication in these proceedings. We would like to thank the participants for their attendance and presentations, making the EFD 2004 as successful as they were. Based on this success, it is our intention to make the EFD into a recurring event. Eindhoven, December 2004 Loek Cleophas Bruce W. Watso

Towards cache optimization in finite automata implementations

To the best of our knowledge, the only available implementations of FA-based string recognizers are the so-called conventional table-driven algorithm and, of course, its hardcoded counterpart suggested by Thompson, Penello, and DeRemer in 1967, 1986, and 2004 respectively. However, our early experiments have shown that the performance of both implementations is hampered by the random access nature of the automaton’s transition table in the case of table-driven, and also the random access nature of the directly executable instructions that make up each hardcoded state. Moreover, the problem of memory load and instruction load are also performance bottlenecks of these algorithms, since, as the automaton size grows, more space in memory is required to hold data/instructions relevant to the states. This thesis exploits the notion of cache optimization (that requires good data or instructions organization) in investigating various enhancements of both table-driven and hardcoding. Functions have been used to formally define the denotational semantics of string recognizers. These functions rely on various so-called strategy variables that are integrated into the formal definition of each recognizer. By appropriately selecting these variables, the conventional algorithms may be described, without loss of generality. By specializing these strategy variables, the new and enhanced recognizers can be denotationally described, and resulting algorithms can then be implemented. We first introduce the so-called Dynamic State Allocation (DSA) strategy regarded as a sort of Just-In-time (JIT) implementation of FA-based string recognizers whereby a predefined portion of the memory is reserved for acceptance testing. Then follows the State pre-Ordering (SpO) strategy that assumes some prior knowledge on the order in which states would be visited. In this case, acceptance testing takes place once each state have been allocated to its new position in memory. The last strategy referred to as the Allocated Virtual Caching (AVC) strategy is based on the premise that a portion of the memory originally occupied by the automaton’s states is virtually used as a sort of cache memory in which acceptance testing takes place, enabling therefore, the exploitation of the various performance enhancement notions on which hardware cache memory relies. It is shown that the algorithms can be classified in a taxonomy tree which is further mapped into a class-diagram that represents the design of a toolkit for FA-based string recognition. Also given in the thesis are empirical results that indicate that the algorithms suggested can, in general, outperform their conventional counterparts when recognizing large and appropriately chosen input strings.Thesis (PhD (Computer Science))--University of Pretoria, 2007.Computer SciencePhDunrestricte

Verifying big data topologies by-design: a semi-automated approach

Big data architectures have been gaining momentum in recent years. For instance, Twitter uses stream processing frameworks like Apache Storm to analyse billions of tweets per minute and learn the trending topics. However, architectures that process big data involve many different components interconnected via semantically different connectors. Such complex architectures make possible refactoring of the applications a difficult task for software architects, as applications might be very different with respect to the initial designs. As an aid to designers and developers, we developed OSTIA (Ordinary Static Topology Inference Analysis) that allows detecting the occurrence of common anti-patterns across big data architectures and exploiting software verification techniques on the elicited architectural models. This paper illustrates OSTIA and evaluates its uses and benefits on three industrial-scale case-studies

Design and Implementation of Cellular Automaton Simulating Domain Growth

Tato bakalářská práce se věnuje návrhu a implementaci grafického uživatelského rozhraní buněčného automatu simulující růst domén. Uživatelské rozhraní je implementováno v jazyce C++ s použitím frameworku Qt. Hlavním požadavkem je intuitivní ovládání a čistý kód, umožňující dalším úpravy programu. Apli\-kace nabízí možnost počátečního rozložení domén a jejich faktoru růstu. Během simulace lze provádět vybrané akce.This bachelor thesis is devoted to design and implementation of the graphical user interface of cellular automaton simulating domain growth. User interface is implemented in C++ with usage of framework Qt. Important elements are intuitive controls of the application and clean code, which allows another program modifications. Application allows user to set initial location of the domains and their growth factor. During simulation user can perform selected actions

Implementation of Code Properties via Transducers

The FAdo system is a symbolic manipulator of formal language objects, implemented in Python. In this work, we extend its capabilities by implementing methods to manipulate transducers and we go one level higher than existing formal language systems and implement methods to manipulate objects representing classes of independent languages (widely known as code properties). Our methods allow users to define their own code properties and combine them between themselves or with fixed properties such as prefix codes, suffix codes, error detecting codes, etc. The satisfaction and maximality decision questions are solvable for any of the definable properties. The new online system LaSer allows one to query about a code property and obtain the answer in a batch mode. Our work is founded on independence theory as well as the theory of rational relations and transducers, and contributes with improved algorithms on these objects