What is the difference between a DFA and an NFA?

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What is the difference between a DFA and an NFA?

The main difference between a Deterministic Finite Automaton (DFA) and a Non-deterministic Finite Automaton (NFA) lies in their transition functions.

In a DFA, for each state and input symbol, there is exactly one transition defined. This means that the DFA can only be in one state at a time and the next state is uniquely determined by the current state and input symbol. DFAs are deterministic in nature, meaning that given a specific input, they will always produce the same output.

On the other hand, an NFA can have multiple transitions defined for a state and input symbol, or even have epsilon transitions (transitions without consuming any input). This allows for non-determinism, as the NFA can be in multiple states simultaneously for a given input symbol. The next state is not uniquely determined, and the NFA can have multiple possible paths to reach a final state.

In summary, the key difference is that a DFA has a unique transition for each state and input symbol, while an NFA can have multiple transitions and allows for non-determinism.