update notations and fix typos

pages/Math4111/Math4111_L22.md

@@ -77,7 +77,7 @@ This proves that $\lim_{n\to\infty} |s_n - t_n| = 0$.
 
 Since $\lim_{n\to\infty} s_n$ exists, $\lim_{n\to\infty} s_n = \lim_{n\to\infty} t_n$.
 
-EOP
+QED
 
 #### Theorem 3.54
 
@@ -137,7 +137,7 @@ Then: $(p_n)$ is a sequence in $E\backslash\{p\}$ with $d_X(p_n,p) = \frac{1}{n}
 
 So $\lim_{n\to\infty} f(p_n) \neq q$.
 
-EOP
+QED
 
 With this theorem, we can use the properties of limit of sequences to study limits of functions.