define dfa and nfa

DFA (Deterministic Finite Automaton) and NFA (Non-deterministic Finite Automaton) are two types of abstract machines used in automata theory, a branch of theoretical computer science. They are used to model and analyze the behavior of systems.

1. DFA (Deterministic Finite Automaton): A DFA is a theoretical model of computation where an automaton reads a string of symbols and changes its state accordingly. It is deterministic in nature, meaning for each input symbol, one can determine the state to which the machine will move. Hence, it is called Deterministic Automaton.

Steps to define DFA:

• A DFA has a finite number of states and rules.
• It has a start state from where any input is processed (computation begins).
• It has a set of final states (also known as accept states) where if DFA gets halted, then it is considered to be accepted.

2. NFA (Non-deterministic Finite Automaton): An NFA is similar to a DFA but differs in that each of its transitions is uniquely determined by its source state and input symbol, and reading an input symbol may result in moving to one, more than one, or no transition state. Hence, it is called Non-deterministic Automaton.

Steps to define NFA:

• An NFA also has a finite number of states and rules.
• It has a start state from where any input is processed.
• It has a set of final states.
• Unlike DFA, NFA can move to any state for a particular input, and even for a null (empty) input.

In summary, the key difference between DFA and NFA is that DFA follows only one path for a specific input, while NFA can follow multiple paths.