Powerset construction in C# (opens in new tab)

Believe it or not, I implemented powerset() as a joke in Gosu years ago:

  var set : java.util.Set<String>  = {"a", "b", "c"}
  print( set.powerSet() )  

prints

  [[], [b], [c], [b, c, a], [a], [b, c], [a, c], [b, a]]

You can try it here (until the Heroku dyno goes down):

  http://gosu-lang.github.io/play.html

The terminology is a little confusing. It's better to call the NFA to DFA algorithm the "subset construction". The power set is a term which is used to denote the set of all subsets of a set. The states of a DFA are not all the possible subsets of the NFA; just those subsets which are generated by epsilon-closures on the state transitions. I.e. the set of DFA states consists of a subset of the power set of the NFA states.