National Repository of Grey Literature 246 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Automata Systems
Petřík, Patrik ; Lukáš, Roman (referee) ; Meduna, Alexandr (advisor)
This work deals with automata systems. We define parallel automata systems and parallel communicating automata systems communicating by transitions, whose components are finite state automata. We investigate their properties compared with grammar systems or grammars.
Formal Language Theory Applied to Computer Security
Regéciová, Dominika ; Kolář, Dušan (referee) ; Meduna, Alexandr (advisor)
Computer security is and will always be a critical area that affects everyone. Despite all the efforts made to build safer systems and test them, however, new vulnerabilities and vulnerabilities are still emerging and creating the impression of tilting at windmills. Partial justification of the current state, but also possible solutions, brings in many respects an extraordinary view of security through formal language theory. Emphasis should be put on a more responsible approach to the recognition and processing of inputs, which are often the gateway to many attacks. In this paper, we will get acquainted with this trend and its recommendations for development and will then introduce a new method of detecting SQL injection attacks built on its foundations.
Code Analysis and Transformation
Křoustek, Jakub ; Masařík, Karel (referee) ; Meduna, Alexandr (advisor)
This paper describes methods and procedures used for code analysis and transformation. It contains basic information of a science discipline called reverse engineering and its use in information technologies. The primary objective is a construction of tool that can disassemble from binary form to symbolic machine code. This operation is highly dependent on the concrete instruction set, and it has to be used for a beforehand known processor architecture. This problem is solved with patterns, plug-ins, and modularity of disassembler. These features provide users the ability to add new instruction sets into this disassembler. The output is the text representation of instructions and is functionally equivalent to the in-put. The thesis demonstrates usual methods of disassembly as well as the methods made by the author.
Predictive Parsing with Deep Pushdowns
Viktorin, Jiří ; Blatný, Petr (referee) ; Meduna, Alexandr (advisor)
This paper introduces a generalization of classical pushdown automata-deep pushdown automata. Deep pushdown automata expand a pushdown symbol in a depth defined by a rule. Deep pushdown expands a non-terminal in the deep defined in the rule and this non-terminal need not be on the top of pushdown.
Parsing Based on Automata with Deep Pushdowns
Pločicová, Dominika ; Dvořák, Tomáš (referee) ; Meduna, Alexandr (advisor)
Language is a basic means of communication. Formal languages provide the basis for human-computer communication. The aim of this work is to contribute to this area and analyze the possibility of processing the context-sensitive elements of formal languages. The work includes the theoretical description of state grammar and deep pushdown automaton, which is a model of a parser for languages including context-sensitive elements. It describes an algorithm that can convert the state grammar to the said deep pushdown automaton. The work further describes parsing, its methods and the use of the created automaton in performing the syntax analysis. For a better understanding, the work also includes examples of the creation and operation of the automaton. Finally, the work describes the implementation of a program that performs theoretically described activities. The functionality of the program was verified on examples, whose inputs and outputs are also part of the text of the work.
Transducer Systems and Their Applications
Lupták, Filip ; Krčmář, Radim (referee) ; Meduna, Alexandr (advisor)
This thesis defines a new formal model „transducer system." Transducer system is composed of a number of finite transducers, which cooperate. The thesis examines expressive power of this formal model and shows that transducer system is more powerful than isolated finite transducer. This model is then used to design a parser of arithmetic expressions, which translates them to postfix notation.
Parallel Versions of General Parsing
Mikita, Tibor ; Kučera, Jiří (referee) ; Meduna, Alexandr (advisor)
This thesis deals with general parsing methods. The author studies the Cocke-Younger-Kasami algorithm and comes up with a design of a parallel version. The motivation of~the author is the acceleration of parsing based on this algorithm. The result is a console application that can determine whether an input string belongs to a language generated by the input grammar or not on the basis of the designed parallel algorithm. For the programming language, C++ was chosen. To achieve parallelism the work of the algorithm was divided among several threads.
Parallel Parsing
Holko, Maroš ; Regéciová, Dominika (referee) ; Meduna, Alexandr (advisor)
The goal of this bachelor thesis is to create and implement a parallel version of a Cocke-Younger-Kasami algorithm, which is used for syntactic analysis. This algorithm works with context-free grammars, so a big part of this work is dedicated to context-free grammars and their transformation to the Chomsky normal form. Output of this thesis is console application in C++ which use threads for parallel processing. There is also an extension for finding all rule successions for given input string designed and implemented. In the end there is a discussion about program's advantages and disadvantages.
A New Approach to LL and LR Parsing
Martiček, Štefan ; Burgetová, Ivana (referee) ; Meduna, Alexandr (advisor)
Cílem této práce je vytvořit nový efektivní způsob syntaktické analýzy propojením LL a LR přístupů. Pro demonstrační účely je zhotoven nový programovací jazyk podle vzoru programovacího jazyka PHP. Tento jazyk je rozdělen na části, kde pro každou část je použita ta nejvhodnejší ze zmíněných metod. Jednotlivé metody jsou zde podrobněji popsané v kontextu dvou typů přístupů. Jedním z nich je syntaktická analýza shora dolů a tím druhým opačná verze, syntaktická analýza zdola nahoru. Pro každou separovanou část je vytvořen samostatný syntaktický analyzátor. Táto práce poskytuje kompletní teoretický základ k sestrojení všech zde použitých syntaktických analyzátorů a rozkladových tabulek. Nakonec jsou sestrojené analyzátory společne propojeny, což je úspěšné zakončení praktické demonstrace naší metody. V závěru jsou diskutovány dosažené výsledky práce jako efektivnejší druh syntaktické analýzy, modularita přístupu a podobně. Je zde také diskutovaná použitelnost navržené metody za účelem zefektivnení vývoje a rychlosti překladu. Jako poslední jsou uvedeny náměty pro další výzkum v této oblasti.
Modified Parsing
Sopuch, Zbyněk ; Rychnovský, Lukáš (referee) ; Meduna, Alexandr (advisor)
This project deals with modification of syntax analysis. I realize three modifications of bottom up algorithm. First way is modification of Cocke-Younger-Kasami algorithm, second is based on EOL system and third is based on ETOL system.

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