Given the following syntax directed translation rules: Rule 1: R AB \B.i = R.i - 1; A.i = B.i; R.i = A.i + 1;\ Rule 2: P CD \P.i = C.i + D.i; D.i = C.i + 2;\ Rule 3: Q EF \Q.i = E.i + F.i;\ Which ONE is the CORRECT option among the following? A) Rule 1 is S-attributed and L-attributed; Rule 2 is S-attributed and not L-attributed; Rule 3 is neither S-attributed nor L-attributed B) Rule 1 is neither S-attributed nor L-attributed; Rule 2 is S-attributed and L-attributed; Rule 3 is S-attributed and L-attributed C) Rule 1 is neither S-attributed nor L-attributed; Rule 2 is not S-attributed and is L-attributed; Rule 3 is S-attributed and L-attributed D) Rule 1 is S-attributed and not L-attributed; Rule 2 is not S-attributed and is L-attributed; Rule 3 is S-attributed and L-attributed

Official answer: C) Rule 1 is neither S-attributed nor L-attributed; Rule 2 is not S-attributed and is L-attributed; Rule 3 is S-attributed and L-attributed. Explanation: To determine whether each syntax-directed definition (SDD) rule is S-attributed or L-attributed, we apply the standard definitions: 1. S-attributed SDD: Uses only synthesized attributes (i.e., attributes of the non-terminal on the LHS are computed solely from attributes of the children on the RHS). 2. L-attributed SDD: Allows both synthesized and inherited attributes. For any production A X1 X2 Xn, an inherited attribute of Xj may depend only on: - Inherited attributes of the head A, and/or - Attributes of symbols X1, X2, , Xj-1 appearing to the left of Xj. *(Every S-attributed SDD is also an L-attributed SDD).* --- ### Analysis of Each Rule: - Rule 1: R AB \B.i = R.i - 1; A.i = B.i; R.i = A.i + 1;\ - In A.i = B.i, the attribute of the symbol A depends on B, which lies to its right. This violates the L-attributed property. - Since it contains inherited attributes (B.i and A.i), it is also not S-attributed. - Therefore, Rule 1 is neither S-attributed nor L-attributed. - Rule 2: P CD \P.i = C.i + D.i; D.i = C.i + 2;\ - P.i = C.i + D.i computes a synthesized attribute for the head P from children C and D. - D.i = C.i + 2 computes an inherited attribute for D using C, which is strictly to the left of D. This satisfies the L-attributed condition. - Because it includes the inherited attribute D.i, it is not S-attributed. - Therefore, Rule 2 is not S-attributed and is L-attributed. - Rule 3: Q EF \Q.i = E.i + F.i;\ - Q.i is computed solely from the attributes of its children E and F. - This uses only synthesized attributes, so it is S-attributed. - Every S-attributed grammar is also L-attributed. - Therefore, Rule 3 is S-attributed and L-attributed. Matching these classifications with the choices gives Option (C) as the correct answer.

A) Rule 1 is S-attributed and L-attributed; Rule 2 is S-attributed and not L-attributed; Rule 3 is neither S-attributed nor L-attributed

B) Rule 1 is neither S-attributed nor L-attributed; Rule 2 is S-attributed and L-attributed; Rule 3 is S-attributed and L-attributed

C) Rule 1 is neither S-attributed nor L-attributed; Rule 2 is not S-attributed and is L-attributed; Rule 3 is S-attributed and L-attributed

D) Rule 1 is S-attributed and not L-attributed; Rule 2 is not S-attributed and is L-attributed; Rule 3 is S-attributed and L-attributed

Compiler Design · Syntax-Directed Translation

Official IIT answer key · IIT Guwahati · Audited Aug 2026

Take topic test

GATE CSE 2025 Set 2 Q22 · MCQ · 1 mark

Given the following syntax directed translation rules: Rule 1: $R \to AB \{B.i = R.i - 1; A.i = B.i; R.i = A.i + 1;\}$ Rule 2: $P \to CD \{P.i = C.i + D.i; D.i = C.i + 2;\}$ Rule 3: $Q \to EF \{Q.i = E.i + F.i;\}$ Which ONE is the CORRECT option among the following?

Select an option to check

Key concept

Syntax-Directed Translation

Step-by-step verified solution

Examiner trap & misconception

Topic notes

How GATE tests Syntax-Directed Translation

Syntax-Directed Translation (SDT/SDD) in GATE CS is consistently tested through two primary angles: theoretical classification (identifying S-attributed vs. L-attributed definitions and parser traversal compatibility) and concrete evaluation (tracing attribute evaluation or action execution for a given input string). Questions routinely evaluate precedence, associativity, base conversions (e.g., binary fractions), type checking, or parse-reduction action sequences.

Full Syntax-Directed Translation guide →

More on Syntax-Directed Translation

All 9 questions on Syntax-Directed Translation →

Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.

Compiler Design · Syntax-Directed Translation

Official IIT answer key · IIT Guwahati · Audited Aug 2026

Take topic test

GATE CSE 2025 Set 2 Q22 · MCQ · 1 mark

Given the following syntax directed translation rules: Rule 1: $R \to AB \{B.i = R.i - 1; A.i = B.i; R.i = A.i + 1;\}$ Rule 2: $P \to CD \{P.i = C.i + D.i; D.i = C.i + 2;\}$ Rule 3: $Q \to EF \{Q.i = E.i + F.i;\}$ Which ONE is the CORRECT option among the following?

Select an option to check

Key concept

Syntax-Directed Translation

Step-by-step verified solution

Examiner trap & misconception

Topic notes

How GATE tests Syntax-Directed Translation

Full Syntax-Directed Translation guide →

More on Syntax-Directed Translation

All 9 questions on Syntax-Directed Translation →

Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.

Given the following syntax directed translation rules: Rule 1: $R \to AB \{B.i = R.i - 1; A.i = B.i; R.i = A.i + 1;\}$ Rule 2: $P \to CD \{P.i = C.i + D.i; D.i = C.i + 2;\}$ Rule 3: $Q \to EF \{Q.i = E.i + F.i;\}$ Which ONE is the CORRECT option among the following?

Step-by-step verified solution

Check you can still solve Syntax-Directed Translation under a clock

More from GATE CSE 2025 Set 2

More on Syntax-Directed Translation

Given the following syntax directed translation rules: Rule 1: $R \to AB \{B.i = R.i - 1; A.i = B.i; R.i = A.i + 1;\}$ Rule 2: $P \to CD \{P.i = C.i + D.i; D.i = C.i + 2;\}$ Rule 3: $Q \to EF \{Q.i = E.i + F.i;\}$ Which ONE is the CORRECT option among the following?

Step-by-step verified solution

Check you can still solve Syntax-Directed Translation under a clock

More from GATE CSE 2025 Set 2

More on Syntax-Directed Translation

Step-by-step verified solution

Check you can still solve Syntax-Directed Translation under a clock

More from GATE CSE 2025 Set 2

More on Syntax-Directed Translation

Share this solution

Step-by-step verified solution

Check you can still solve Syntax-Directed Translation under a clock

More from GATE CSE 2025 Set 2

More on Syntax-Directed Translation

Share this solution