Question

Distinguish between dfa and nfa?

Answer 1

DFA only has one state transition for every symbol of the alphabet, and there is only one final state for its transition which means that for each character that is read, there is one corresponding state in DFA. It is easier to check membership in DFA but it is more difficult to construct. Backtracking is allowed in DFA, and it requires more space than NFA.
Backtracking is not always allowed in NFA. While it is possible in some cases, in others it is not. It is easier to construct NFA, and
it also requires less space, but it is not possible to construct an NFA machine for every input and output.

The theory of computation is a branch of computer science that deals with how problems are solved using algorithms. It has three branches, namely; the computational complexity theory, the computability theory, and the automaton theory.
The automaton or automata theory is the study of abstract mathematical machines or systems that can be used to solve computational problems. An automaton is made up of states and transitions, and as it sees a symbol or letter of input, it makes a transition to another state taking the current state and symbol as input.