Description:

Students are introduced to basic theoretical and implementation principles of the following topics: construction, use and mutual transformations of finite automata, regular expressions and regular grammars, translation finite automata, construction and use of pushdown automata, hierarchy of formal languages, relationships between formal languages and automata. Knowledge acquired through the module is applicable in designs of algorithms for searching in text, data compression, simple parsing and translation, and design of digital circuits.

Contents:

1. Motivation to study formal languages. Basic notions (language, alphabet, grammar, automaton), Chomsky hierarchy.
2. Nondeterministic and deterministic finite automata (NFA, DFA), NFA with epsilon transitions.
3. Operations on automata (transformation to NFA without epsilon transitions, to DFA, minimization), intersection, union.
4. Programming implementations of DFA and NFA, circuit implementations.
5. Adding translation, Mealey, Moore, conversions.
6. Operations on regular grammars, conversions to FA.
7. Regular expressions, regular expression conversions, finite automata and regular grammars, Kleene theorem.
8. Principles of use of regular expressions in UNIX (grep, egrep, perl, PHP, ...).
9. Finite automaton as a lexical analyzer, lex/flex generators.
10. Properties of regular languages (pumping lemma, Nerode theorem).
11. Context-free languages, pushdown automaton.
12. Parsing of context-free languages (nondeterministic versus deterministic).
13. Context-sensitive and recursively enumerable languages, Turing machine. Classes P, NP, NPC, NPH

Seminar contents:

1. Implementation of FA.
2. Examples of formal languages. Intuitive considerations of grammars for given languages. Estimation of the classification of a given language in Chomsky hierarchy.
3. Intuitive creation of finite automata (DFA, NFA, with epsilon transitions) for a given langauage.
4. Transformations and compositions of FA.
5. FA with output function and its implementation.
6. Conversions of grammars to FA and vice versa.
7. Considerations, modifications and transformations of regular expressions.
8. Use of regular expressions for text processing tasks (e.g. sh, grep, sed, perl).
9. Creation and implementation of lexical analyzers.
10. Classification of languages.
11. Examples of context-free languages, creation of pushdown automata.
12. Examples of deterministic parsing of context-free languages (e.g. LL, yacc, bison).
13. Examples of context-sensitive and recursively enumerable languages, creation of grammars, creation of Turing machines.

Recommended literature:

1. Sipser M. : Introduction to the Theory of Computation. Cengage Learning Custom Publishing, 2020. ISBN 978-0357670583.
2. Hopcroft J.E., Motwani R., Ullman J. D. : Introduction to Automata Theory, Languages, and Computation, 3rd Edition. Pearson, 2008. ISBN 978-8131720479.
3. Kozen D. C. : Automata and Computability. Springer, 1997. ISBN 978-0387949079.

Abbreviations used:

Semester:

• W ... winter semester (usually October - February)
• S ... spring semester (usually March - June)
• W,S ... both semesters

Mode of completion of the course:

• A ... Assessment (no grade is given to this course but credits are awarded. You will receive only P (Passed) of F (Failed) and number of credits)
• GA ... Graded Assessment (a grade is awarded for this course)
• EX ... Examination (a grade is awarded for this course)
• A, EX ... Examination (the award of Assessment is a precondition for taking the Examination in the given subject, a grade is awarded for this course)

Weekly load (hours per week):

• P ... lecture
• C ... seminar
• L ... laboratory
• R ... proseminar
• S ... seminar