# What is regular expression in finite automata?

## What is regular expression in finite automata?

The language accepted by finite automata can be easily described by simple expressions called Regular Expressions. A regular expression can also be described as a sequence of pattern that defines a string. Regular expressions are used to match character combinations in strings.

### What is the relationship between regular expressions and finite automata?

Finite automata are formal (or abstract) machines for recognizing patterns. These machines are used extensively in compilers and text editors, which must recognize patterns in the input. Regular expressions are a formal notation for generating patterns.

**What language does the regular expression AAB * AB )* represent?**

Yes, a*b* represents a regular language. Language description: Any number of a followed by any numbers of b (by any number I mean zero (including null ^ ) or more times). Some example strings are: {^, a, b, aab, abbb, aabbb.}

**What are the application of regular expressions and finite automata?**

Finite Automata (FA) – For the designing of lexical analysis of a compiler. For recognizing the pattern using regular expressions. For the designing of the combination and sequential circuits using Mealy and Moore Machines. Used in text editors.

## What is the relation between the tuple Q and F for the finite automata?

1) Deterministic Finite Automata (DFA) – ( Symbols which machine takes as input ) q : Initial state. ( Starting state of a machine ) F : set of final state. δ : Transition Function, defined as δ : Q X Σ –> Q. In a DFA, for a particular input character, the machine goes to one state only.

### Which language is accepted by finite automata *?

A regular language satisfies the following equivalent properties: it is the language of a regular expression (by the above definition) it is the language accepted by a nondeterministic finite automaton (NFA)

**What will be the regular expression for this regular set ABB AB BBA?**

and (a+b)*={null,a,b,aa,bb,ab,abb,bbb,aab,……..} so option c is correct….Discussion Forum.

Que. | Regular expression for all strings starts with ab and ends with bba is. |
---|---|

b. | ab(ab)*bba |

c. | ab(a+b)*bba |

d. | All of the mentioned |

Answer:ab(a+b)*bba |