--- a/re3.scala	Mon Nov 05 20:31:58 2012 +0000
+++ b/re3.scala	Sun Nov 11 17:28:11 2012 +0000
@@ -32,11 +32,12 @@
   }
 }
 case class NTIMES(r: Rexp, n: Int) extends Rexp {
-  override def simp = r.simp match {
-    case NULL => NULL
-    case EMPTY => EMPTY
-    case r => NTIMES(r, n)
-  }
+  override def simp = if (n == 0) EMPTY else 
+    r.simp match {
+      case NULL => NULL
+      case EMPTY => EMPTY
+      case r => NTIMES(r, n)
+    }
 }
 
 // some convenience for typing in regular expressions
@@ -57,7 +58,7 @@
   case ALT(r1, r2) => nullable(r1) || nullable(r2)
   case SEQ(r1, r2) => nullable(r1) && nullable(r2)
   case STAR(_) => true
-  case NTIMES(r, i) => if (i == 0) false else nullable(r)
+  case NTIMES(r, i) => if (i == 0) true else nullable(r)
 }
 
 // derivative of a regular expression w.r.t. a character
@@ -88,13 +89,6 @@
 //one or zero
 def OPT(r: Rexp) = ALT(r, EMPTY)
 
-//n-times
-/*def NTIMES(r: Rexp, n: Int) : Rexp = n match {
-  case 0 => NULL
-  case 1 => r
-  case n => SEQ(r, NTIMES(r, n - 1))
-}*/
-
 def RTEST(n: Int) = SEQ(NTIMES(OPT("a"), n), NTIMES("a", n))
 
 def time_needed[T](i: Int, code: => T) = {
@@ -105,8 +99,8 @@
 }
 
 
-for (i <- 1 to 10001 by 500) {
-  println(i + " " + time_needed(1, matcher(RTEST(i), "a" * i)))
+for (i <- 1 to 11001 by 500) {
+  println(i + " " + + " " + time_needed(1, matcher(RTEST(i), "a" * i)))
 }