Difference between DFA and NFA

Difference between DFA and NFA in Tabular Form

DFA and NFA Difference

  • NFA is Called a Nondeterministic Finite Automaton. DFA is called a Deterministic Finite Automaton. The Key Difference between DFA and NFA is in the below table.

DFA and NFA Comparison Chart

DFA stands for Deterministic Finite Automata. NFA stands for Non-Deterministic Finite Automata.
When processing a string in DFA, there is always a unique state to go next when each character is read. It is because, for each state in DFA, there is exactly one state that corresponds to each character being read. In NFA several choices may exist for the next state. Can move to more than one state.
DFA can not use empty string transition. NFA can use empty string transition.
In DFA we cannot move from one state to another without consuming a symbol. NFA allows € (null) as the second argument of the transition function. This means that the NFA can make a transition without consuming an input symbol.
For every symbol of the alphabet, there is only one state transition in DFA. We do not need to specify how does the NFA react according to some symbol.
DFA can be understood as one machine. NFA can be understood as multiple title machines computing at the same time.
DFA will reject the string if it ends at other than accepting the state If all the branches of NFA die or reject the string, we can say that NFA rejects the string.
It is more difficult to construct DFA. NFA is easier to construct.
DFA requires more space. NFA requires less space.
For every input and output, we can construct a DFA machine. It is not possible to construct an NFA machine for every input and output.
All DFA is NFA. Not all NFA is DFA.
Backtracking is allowed in DFA backtracking is not allowed in NFA

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