Add solutions

15/induktion.txt

+IV
+
+(reverse . map f) xs = (map f . reverse) xs
+reverse (map f xs) = map f (reverse xs)
+
+
+IS
+
+xs = (x:xs)
+
+(reverse . map f) (x:xs)
+    = reverse (map f (x:xs))
+    = reverse (f x : (map f xs))
+    = reverse (map f xs) ++ [f x]
+    = map f (reverse xs) ++ [f x]
+    = map f (reverse xs) ++ map f [x]
+    = map f (reverse xs ++ [x])
+    = map f (reverse (x:xs))
+    = (map f . reverse) (x:xs)

15/lösungen.hs

+data Set = Union Set Set | Intersection Set Set | Complement Set | Set Char deriving Show
+
+
+deMorgan (Complement (Union a b))        = Intersection (Complement a) (Complement b)
+deMorgan (Complement (Intersection a b)) = Union (Complement a) (Complement b)
+
+deMorgan (Complement x) = Complement (deMorgan x)
+deMorgan (Intersection x y) = Intersection (deMorgan x) (deMorgan y)
+deMorgan (Union x y) = Union (deMorgan x) (deMorgan y)
+deMorgan x = x