diff --git a/scsh/test/pattern-matching-test.scm b/scsh/test/pattern-matching-test.scm
index 226fb86..d00b54f 100644
--- a/scsh/test/pattern-matching-test.scm
+++ b/scsh/test/pattern-matching-test.scm
@@ -496,7 +496,13 @@
 	    (match:substring (string-match (uncase (rx "foo"))
 					   "FoO")))))
 
-;; XXX no idea how to test simplify-regexp
+(add-test! 'simplify-regexp-test 'pattern-matching
+  (lambda ()
+    (and (re-dsm? (rx (: (** 0 0 (submatch "apple"))
+			 (submatch "bar"))))
+	 (= 2
+	    (re-dsm:tsm (rx (: (** 0 0 (submatch "apple"))
+			       (submatch "bar"))))))))
 
 
 
@@ -533,3 +539,59 @@
 ;						 (re-repeat 1 #f (re-string "Sz"))
 ;						 (re-string "ilagyi")))))))
 
+(add-test! 'char-classes+algebra-test 'pattern-matching
+  (lambda ()
+    (and (matches-same-signs? (rx (| lower-case upper-case))
+			      (rx alphabetic))
+	 (matches-same-signs? (rx (- alphabetic lower-case))
+			      (rx upper-case))
+	 (matches-same-signs? (rx (- alphabetic upper-case))
+			      (rx lower-case))
+	 (matches-same-signs? (rx (& upper-case alphanumeric))
+			      (rx upper-case))
+	 (matches-same-signs? (rx (| upper-case lower-case numeric))
+			      (rx alphanumeric))
+	 (matches-same-signs? (rx (~ (& alphanumeric lower-case)
+				     graphic
+				     (| upper-case numeric)))
+			      (rx (- any 
+				     alphanumeric
+				     graphic)))
+	 (matches-same-signs? (rx (/ "azAZ09"))
+			      (rx alphanumeric))
+	 (matches-same-signs? (rx (~ (| (/ "az") (/ "AZ") (/ "09"))))
+			      (rx (- any alphanumeric)))
+	 (matches-same-signs? (rx (& (/ "az09") 
+				     (/ "AZ09")))
+			      (rx numeric)))))
+
+(add-test! 'different-ways-test 'pattern-matching
+  (lambda ()
+    (and (eq-match? (string-match (rx "abcde") "xxxabcdexxx")
+		    (string-match (rx (: "a" "b" "c" "d" "e")) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx "abcde") "xxxabcdexxx")
+		    (string-match (rx (: "a" (: "b" (: "c" (: "d" "e"))))) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx "abcde") "xxxabcdexxx")
+		    (string-match (rx (: "ab" "c" (: "d" "e"))) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx "abcde") "xxxabcdexxx")
+		    (string-match (rx (: "a" "b" "cde")) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx "abcde") "xxxabcdexxx")
+		    (string-match (rx (: (: (: "a" "b") "c") (: "d" "e"))) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx "xxx" (* alphabetic) "xxx") "xxxabcdexxx")
+		    (string-match (rx (+ "x") "abcde" (+ "x")) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx (: "x" (+ "x") (* "x"))
+				      (: (? alphanumeric)
+					 (? alphanumeric)
+					 (? alphanumeric)
+					 (? alphanumeric)
+					 (? alphanumeric)
+					 (? alphanumeric)
+					 (? alphanumeric)
+					 (? alphanumeric))
+				      "xxx") 
+				  "xxxabcdexxx")
+		    (string-match (rx (: "xxx" (* (/ "ae")) (+ "x"))) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx "xxxabcdexxx") "xxxabcdexxx")
+		    (string-match (rx (* alphanumeric)) "xxxabcdexxx"))
+	 (eq-match? (string-match (rx (: "xxx" (: "abcde" "x" "xx"))) "xxxabcdexxx")
+		    (string-match (rx (* (| (/ "ae") "x"))) "xxxabcdexxx")))))