update notations and fix typos

pages/CSE347/CSE347_L7.md

@@ -154,7 +154,7 @@ This is a valid assignment since:
 - We pick either $v_i$ or $\overline{v_i}$
 - For each clause, at least one literal is true
 
-EOP
+QED
 
 Claim 2: If $\Psi$ is satisfiable, then Subset Sum has a solution.
 
@@ -174,7 +174,7 @@ Say $t=\sum$ elements we picked from $S$.
   - If $q_j=2$, then $z_j\in S'$
   - If $q_j=3$, then $y_j\in S'$
 
-EOP
+QED
 
 ### Example 2: 3 Color
 
@@ -228,13 +228,13 @@ For each dangler color is connected to blue, all literals cannot be blue.
 
 ...
 
-EOP
+QED
 
 Direction 2: If $G$ is 3-colorable, then $\Psi$ is satisfiable.
 
 Proof:
 
-EOP
+QED
 
 ### Example 3:Hamiltonian cycle problem (HAMCYCLE)