GATE CS 2015 Set 3 — Question 15

MCQ+1 / -0.33EasyLR(0) & SLR(1)Syntax AnalysisCompiler DesignCLR(1) & LALR(1)

Compiler Design → Syntax Analysis → CLR(1) & LALR(1)

Last updated 5 September 2026

Question

Among simple LR (SLR) , canonical LR, and look-ahead LR (LALR), which of the following pairs identify the method that is very easy to implement and the method that is the most powerful , in that order?

Correct answer (C) SLR, canonical LR Solution 1. SLR (Simple LR): Is the simplest to implement as it uses the LR(0) items and simple follow sets for reduction lookaheads. It has the smallest parsing table size (same as LR(0)) but is the least powerful of the three. 2. Canonical LR (CLR): Is the most powerful method as it uses LR(1) items with specific lookaheads. However, it generates a very large number of states, making it difficult to implement due to table size. 3. LALR (Look-Ahead LR): Is an intermediate method that merges states from CLR to reduce table size (same size as SLR) but is more powerful than SLR. Therefore, the easiest to implement is SLR and the most powerful is canonical LR . Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (C) SLR, canonical LR Solution 1. SLR (Simple LR): Is the simplest to implement as it uses the LR(0) items and simple follow sets for reduction lookaheads. It has the smallest parsing table size (same as LR(0)) but is the least powerful of the three. 2. Canonical LR (CLR): Is the most powerful method as it uses LR(1) items with specific lookaheads. However, it generates a very large number of states, making it difficult to implement due to table size. 3. LALR (Look-Ahead LR): Is an intermediate method that merges states from CLR to reduce table size (same size as SLR) but is more powerful than SLR. Therefore, the easiest to implement is SLR and the most powerful is canonical LR .

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