# What is DFA example?

## What is DFA example?

Deterministic finite automata (or DFA) are finite state machines that accept or reject strings of characters by parsing them through a sequence that is uniquely determined by each string. The term “deterministic” refers to the fact that each string, and thus each state sequence, is unique.

## How is DFA calculated?

A DFA is represented by digraphs called state diagram. The vertices represent the states. The arcs labeled with an input alphabet show the transitions. The initial state is denoted by an empty single incoming arc….Example.

Present State | Next State for Input 0 | Next State for Input 1 |
---|---|---|

a | a | b |

b | c | a |

c | b | c |

**Can DFA have 2 final states?**

In DFA, there is only one path for specific input from the current state to the next state. DFA does not accept the null move, i.e., the DFA cannot change state without any input character. DFA can contain multiple final states. It is used in Lexical Analysis in Compiler.

**Which are the following rules need to be followed by DFA?**

Steps To Construct DFA- Step-01: Determine the minimum number of states required in the DFA. Draw those states. Step-02: Decide the strings for which DFA will be constructed. Step-03: Construct a DFA for the strings decided in Step-02.

### Can a DFA have infinite states?

The language accepted by a DFA M with n states is infinite if and only if M accepts a string of length k, where n≤k<2n.

### Can a DFA have no final states?

Yes Possible. If an automata is not acceptor but transducer then final state is not needed. Any class of an automata can be without a final state!

**Can a DFA have 0 states?**

**Can a null string be accepted by DFA?**

Yes. This is immediate from the definitions. A DFA accepts if it’s in an accepting state after it’s read its input. If the input is the empty string, the DFA makes no transitions so, after reading it’s input, it’s still in its initial state, q0.

#### Can a DFA have zero states?

#### What is the minimum number of states in DFA?

To get the minimum number of states in such a DFA, we can use the Myhill-Nerode theorem beginning with the empty string:

- the empty string can be followed by any string in the language.
- the string 0 cannot be followed by anything since valid base-3 representations don’t have leading 0s.

**What is DFA state invariant?**

Page 19. State Invariant. 19. A state invariant gives, for a state q of a DFA, what we know to be true of exactly those strings that reach q. ● All strings w reaching q must be satisfy P(w)

**Can DFA have multiple transitions?**

My answer is an unequivocal: No. A deterministic finite automata does not need a transition from every state for every symbol. The meaning when δ(q,a) does not exist is simply that the DFA does not accept the input string.

## How many transitions can enter a state in a DFA?

one transition

A DFA has exactly one transition from every state on every symbol in the alphabet.

## Is DFA finite or infinite?

A DFA accepts infinitely many strings iff there exists a loop in the path from initial state to final state.

**Can a DFA have an unreachable state?**

Minimal DFA Unreachable states are the states that are not reachable from the initial state of the DFA, for any input string. These states can be removed. Dead states are the states from which no final state is reachable. These states can be removed unless the automaton is required to be complete.

**How does DFA calculate states?**

STEPS:

- Check, if n is equal to the format 2^k (like 4 = 2^2, 8 = 2^3) , where k is any whole number.
- if n= 2^k. then minimum no of states will be k+1.
- But, if not n != 2^k. Check if n/2 is odd, then minimum states will be n/2+1.

### Is number of state in DFA & NFA are same?

NFA stands for Nondeterministic Finite Automata. For each symbolic representation of the alphabet, there is only one state transition in DFA. No need to specify how does the NFA react according to some symbol. DFA cannot use Empty String transition.

### Can DFA have isolated states?

You are indeed allowed to have unreachable states in DFAs (or NFAs, or various other automata models).

**Can DFA have null transition?**

DFA doesn’t have epsilon transitions. If it had it, it could transit from current state to other state without any input i.e. with nothing , not even {} or phi.

**Can DFA have no transition?**

#### Can a DFA recognize a palindrome number?

Can a DFA recognize a palindrome number? Explanation: Language to accept a palindrome number or string will be non-regular and thus, its DFA cannot be obtained.

#### Why do we minimize DFA?

Minimization of DFA means reducing the number of states from given FA. Thus, we get the FSM(finite state machine) with redundant states after minimizing the FSM.

**Can a DFA have two initial states?**

As per the definition of DFA, so as NFA it can have only one initial state.

**Why NFA is non deterministic?**

NFA stands for non-deterministic finite automata. It is easy to construct an NFA when compared to DFA for a given regular language. The finite automata are called NFA when there exist many paths for specific input from the current state to the next state. Each NFA can be translated into DFA but every NFA is Non DFA.

## Can DFA accept epsilon?

Epsilon move isn’t allow in DFA, because it’ll change DFA into NFA.