diff --git a/exercise-sep-2.txt b/exercise-sep-2.txt
index fbb8fb0..0d866fd 100644
--- a/exercise-sep-2.txt
+++ b/exercise-sep-2.txt
@@ -13,3 +13,10 @@ AuB = {1, 2, 3, 5, 7, 9}
 A↓uB = {3, 7}
 A\B = {1, 9}
 A"delt"B = {1, 2, 5, 9}
+
+
+Beviska: 
+1) ¨A↓u(AuB) = B\A
+   
+2) (AuB)↓u¨(A↓uB) = (A↓u¨B)u(B↓u¨A)
+
diff --git a/notes-sep-2.txt b/notes-sep-2.txt
index fc839e2..f0d9014 100644
--- a/notes-sep-2.txt
+++ b/notes-sep-2.txt
@@ -19,3 +19,7 @@ Räkne regler:
     x € ¨(AuB) => x !€ AuB => {x !€ A, x !€ B => x !€ {x € ¨A, x € ¨B => x € ¨(AuB). Visar att ¨(AuB) …c A↓uB.
     x € ¨A↓u¨B => {x € ¨A, x € ¨B => {x !€ A, x !€ B => x !€ AuB => x € ¨(AuB). Visar att ¨A↓uB …c ¨(AuB).
     Resultat: ¨(AuB) = ¨Au¨B
+- Distributiv: (AuB)↓uC <=> (A↓uC)u(B↓uC), (A↓uB)uC <=> (AuC)↓u(BuC)
+- Absorbering: A↓u(AuB) = A, Au(A↓uB) = A
+- Differens: A\B <=> A↓u¨B
+