Consider the grammar with nonterminals N = {S, C, S₁} terminals T = {a, b, i, t, e} With S as the start symbol , and the following set of rules :

S → i Ct SS₁|a

S₁ → es | ∈

C → b

The grammar is not LL(1) because : 

The correct answer is It is left recursive.

Key Points

• The grammar is not LL(1) because it is left recursive.
• Left recursion in a grammar occurs when a non-terminal appears as the first symbol on the right-hand side of its own production.
• In this grammar, the production rule S → i Ct SS1 indicates that the non-terminal S is left recursive.
• Due to this left recursion, it is not possible to construct a predictive parser (such as an LL(1) parser) since it relies on the first symbol of the production.
• An LL(1) parser requires that the first symbol of each production is unique to make a decision, which is not possible in the presence of left recursion.

Additional Information

• To convert this grammar to an LL(1) grammar, left recursion must be eliminated.
• This can be achieved by transforming the grammar into an equivalent one without left recursion.
• For example, the production S → i Ct SS1 | a can be transformed by introducing new non-terminals and adjusting the rules accordingly.
• Eliminating left recursion ensures that the parser can make decisions based on the first symbol of the production, making it suitable for LL(1) parsing.