diff -r 7a0735db4788 -r b73e7ce91c10 main_solution3/re.scala
--- a/main_solution3/re.scala	Mon Nov 14 12:04:21 2022 +0000
+++ b/main_solution3/re.scala	Thu Nov 17 11:34:50 2022 +0000
@@ -113,7 +113,6 @@
 //println(simp(((CHAR('a') | ZERO) ~ ONE) | 
 //              (((ONE | CHAR('b')) | CHAR('c')) ~ (CHAR('d') ~ ZERO))))
 
-
 // (7) 
 
 def ders (s: List[Char], r: Rexp) : Rexp = s match {
@@ -191,3 +190,12 @@
 
 }
 
+
+
+
+
+/*
+// if nullable(r1)  
+  ALTs(SEQs(der(c, r1)::rs)::(rs filter what is nullable) .map(der(c,_)))
+
+*/
\ No newline at end of file