--- a/progs/enfa.scala	Sat Jul 04 16:58:12 2020 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,66 +0,0 @@
-// epsilon NFAs...immediately translated into NFAs
-// (needs :load dfa.scala 
-//        :load nfa.scala in REPL)
-
-// a fixpoint construction
-import scala.annotation.tailrec
-@tailrec
-def fixpT[A](f: A => A, x: A): A = {
-  val fx = f(x)
-  if (fx == x) x else fixpT(f, fx) 
-}
-
-// translates eNFAs directly into NFAs 
-def eNFA[A, C](starts: Set[A],                     // the starting states
-               delta: (A, Option[C]) :=> Set[A],   // the epsilon-transitions
-               fins: A => Boolean) : NFA[A, C] = { // the final states 
-
-  // epsilon transitions
-  def enext(q: A) : Set[A] = 
-    applyOrElse(delta, (q, None))
-
-  def enexts(qs: Set[A]) : Set[A] = 
-    qs | qs.flatMap(enext(_))     // | is the set-union in Scala
-
-  // epsilon closure
-  def ecl(qs: Set[A]) : Set[A] = 
-    fixpT(enexts, qs)
-
-  // "normal" transitions
-  def next(q: A, c: C) : Set[A] = 
-    applyOrElse(delta, (q, Some(c)))
-
-  def nexts(qs: Set[A], c: C) : Set[A] = 
-    ecl(ecl(qs).flatMap(next(_, c)))
-
-  // result NFA
-  NFA(ecl(starts), 
-      { case (q, c) => nexts(Set(q), c) }, 
-      q => ecl(Set(q)) exists fins)
-}
-
-
-// eNFA examples
-val enfa_trans1 : (State, Option[Char]) :=> Set[State] =
-  { case (Q0, Some('a')) => Set(Q0)
-    case (Q0, None) => Set(Q1, Q2)
-    case (Q1, Some('a')) => Set(Q1)
-    case (Q2, Some('b')) => Set(Q2) 
-  }
-
-val enfa1 = eNFA(Set[State](Q0), enfa_trans1, Set[State](Q2))
-
-
-//
-case object R1 extends State
-case object R2 extends State
-case object R3 extends State
-
-val enfa_trans2 : (State, Option[Char]) :=> Set[State] =
-  { case (R1, Some('b')) => Set(R3)
-    case (R1, None) => Set(R2)
-    case (R2, Some('a')) => Set(R1, R3) 
-  }
-
-
-val enfa2 = eNFA(Set[State](R1), enfa_trans1, Set[State](R3))