Update HOME_EXAM.md

HOME_EXAM.md

@@ -332,7 +332,7 @@ Declares the variable $`v`$ with type $`t`$ to current scope.
 
 ### If true/false expression
 ```math
-\frac{<e, σ> ⇓ true <c1, σ> ⇓ σ'}{<\text{if } b \text{ then }c1> ⇓ σ}
+\frac{<b, σ> ⇓ true <c_1, σ> ⇓ σ'}{<\text{if } b \text{ then }c_1 \text{ else } c_2,σ> ⇓ σ'}
 ```
 
 ### While expression