In the theory of computation, the powerset construction or subset construction is a standard method for converting a nondeterministic finite automaton (NFA) into a deterministic finite automaton (DFA) which recognizes the same formal language. It is important in theory because it establishes that NFAs, despite their additional flexibility, are unable to recognize any language that cannot be recognized by some DFA. It is also important in practice for converting easier-to-construct NFAs into more efficiently executable DFAs. However, if the NFA has n states, the resulting DFA can have up to 2^n states, exponentially more, which sometimes makes the construction impractical in practice for large NFAs.
Reference:
http://en.wikipedia.org/wiki/Powerset_construction
Reference:
http://en.wikipedia.org/wiki/Powerset_construction
