## How do I convert a regular expression to a DFA?

7.2 Algorithm for converting DFA/NFA to Regular Expression

1. Modify the the original machine. Add a new start state with a λ transition to the old start state.
2. Pick an internal state (not the start state or the final state) to “rip out”.
3. Repeat step 2 until the only states left are the start state and the final state.

Can a DFA is derived from regular expression?

One approach to converting a DFA into an equivalent RE is to successively replace states and transitions in the DFA graph with transitions labeled with the equivalent regular expressions. Note that initially, every transition in the DFA is de facto labeled with a regular expression.

### Does DFA accept regular language?

A regular language satisfies the following equivalent properties: it is the language accepted by a nondeterministic finite automaton (NFA) it is the language accepted by a deterministic finite automaton (DFA)

How do you prove a language isn’t regular?

Method to prove that a language L is not regular

1. Select w such that |w| ≥ c.
2. Select y such that |y| ≥ 1.
3. Select x such that |xy| ≤ c.
4. Assign the remaining string to z.
5. Select k such that the resulting string is not in L.

## What is the language accepted by this DFA?

Only finite languages are accepted by DFAs. Every infinite language is accepted by some DFA. infinitely many state but finitely many accept states.

Can a DFA have all final states?

The finite automata are called deterministic finite automata if the machine is read an input string one symbol at a time. In DFA, there is only one path for specific input from the current state to the next state. DFA can contain multiple final states. It is used in Lexical Analysis in Compiler.

### What is a B in regular expression?

ɸ is a regular expression for regular language ɸ. If a and b are regular expression, a + b is also a regular expression with language {a,b}. If a and b are regular expression, ab (concatenation of a and b) is also regular. If a is regular expression, a* (0 or more times a) is also regular.

What is the language accepted by DFA?

A language L is accepted by a DFA < Q , , q0 , , A > , if and only if L = { w | *( q0 , w ) A } . That is, the language accepted by a DFA is the set of strings accepted by the DFA.

## Which string is not accepted by the following DFA?

Explanation: As the initial state is not made an acceptance state, thus ε will not be accepted by the given DFA.