diff -r 6bb7810d2108 -r 37e659cfbb2e marking4/re1b_test.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/marking4/re1b_test.scala	Fri Nov 30 14:13:11 2018 +0000
@@ -0,0 +1,8 @@
+
+import CW8a._
+
+assert(der('a', ZERO | ONE) == (ZERO | ZERO))
+assert(der('a', (CHAR('a') | ONE) ~ CHAR('a')) == ALT((ONE | ZERO) ~ CHAR('a'), ONE))
+assert(der('a', (CHAR('a') | CHAR('a')) ~ CHAR('a')) == (ONE | ONE) ~ CHAR('a'))
+assert(der('a', STAR(CHAR('a'))) == (ONE ~ STAR(CHAR('a'))))
+assert(der('b', STAR(CHAR('a'))) == (ZERO ~ STAR(CHAR('a'))))