diff -r d9d4146325d9 -r 2a128087215f exps/bit-test.scala
--- a/exps/bit-test.scala	Thu May 23 13:30:09 2019 +0100
+++ b/exps/bit-test.scala	Tue Jun 11 00:26:42 2019 +0100
@@ -674,7 +674,7 @@
 //tests derivatives and bsimp
 
 def tests_ders_bsimp(ss: Set[String])(r: Rexp) = {
-  val a = internalise(r)
+  val a = fuse(List(Z,Z,S), internalise(r))
   for (s <- ss.par) yield {  
     val d1 = bsimp(bders(s.toList, bsimp(a)))
     val d2 = bsimp(bders(s.toList, a))
@@ -688,7 +688,7 @@
 
 println("Partial searching: ")
 enum(2, "abc").map(tests_ders_bsimp(strs(1, "abc"))).
-  flatten.toSet.flatten.minBy(a => asize(a._1))
+  flatten.toSet.flatten
 
 // tests about good
 def good(a: ARexp) : Boolean = a match {