Theory-of-Computation

Question 34

The grammar whose productions are

  → if id then 
  → if id then   else 
  → id := id

is ambiguous because

A	the sentence if a then if b then c:=d
B	the left most and right most derivations of the sentence if a then if b then c:=d give rise top different parse trees
C	the sentence if a then if b then c:=d else c:=f has more than two parse trees
D	the sentence if a then if then c:=d else c:=f has two parse trees

Question 34 Explanation:

We have to generate
“if a then if b then c:=d else c:=f”.
Parse tree 1:

Parse tree 2:

Correct Answer: D

Question 34 Explanation:

We have to generate
“if a then if b then c:=d else c:=f”.
Parse tree 1:

Parse tree 2: