ch1_6 - Sep. 13, 2010 (Monday) Chapter 1: Regular Languages...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 1: Regular Languages 7 Regular Expressions In the last class, we showed that the set of languages recognized by DFAs is the same as that recognized by NFAs (i.e. DFAs=NFAs). That is, if a language is recognized by an NFA, it is also regular. In this class, we will study a new way “Regular Expression” (RE) to describe a regular language, and we will show that REs = NFAs = DFAs. Finite Automata Expressions Regular Nondeterministic Finite Autonata Deterministic 7.1 Defnition oF a regular expression R is a regular expression over an alphabet Σ , if R is regular expressions languages a for some a in Σ { a } ε { ε } {} R 1 R 2 L ( R 1 ) L ( R 2 ) R 1 R 2 = R 1 R 2 L ( R 1 ) L ( R 2 ) R * 1 L ( R 1 ) * where R 1 and R 2 are regular expressions If there are multiple operations in a regular expression, we follow the following order: the star operation the concatenation operation the union operation But if a regular expression has parentheses, then we do the operations in the parentheses ±rst. 16
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/30/2010 for the course CSE 434sd taught by Professor Csczdxc during the Spring '10 term at Harding.

Page1 / 2

ch1_6 - Sep. 13, 2010 (Monday) Chapter 1: Regular Languages...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online