GATE CS 2019 Set 1 — Question 13

MCQ+1 / -0.33EasySyntax AnalysisCompiler DesignLR(0) & SLR(1)CLR(1) & LALR(1)

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

Last updated 5 September 2026

Question

Which one of the following kinds of derivation is used by LR parsers?

Correct answer (D) Rightmost in reverse Solution LR parsers are Bottom-Up parsers. Top-Down parsers (like LL parsers) generate the string from the start symbol using Leftmost derivation . Bottom-Up parsers (like LR parsers) start from the input string and reduce it to the start symbol. This reduction process is the reverse of a derivation. Specifically, at each step, an LR parser reduces the handle, which corresponds to reversing a step in a Rightmost derivation . Thus, LR parsers use Rightmost derivation in reverse . Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (D) Rightmost in reverse Solution LR parsers are Bottom-Up parsers. Top-Down parsers (like LL parsers) generate the string from the start symbol using Leftmost derivation . Bottom-Up parsers (like LR parsers) start from the input string and reduce it to the start symbol. This reduction process is the reverse of a derivation. Specifically, at each step, an LR parser reduces the handle, which corresponds to reversing a step in a Rightmost derivation . Thus, LR parsers use Rightmost derivation in reverse .

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