GATE CS 2015 Set 1 — Question 18

MCQ+1 / -0.33MediumLR(0) & SLR(1)Syntax AnalysisCompiler Design

Compiler Design → Syntax Analysis → LR(0) & SLR(1)

Last updated 5 September 2026

Question

Which one of the following is TRUE at any valid state in shift-reduce parsing?

Correct answer (C) The stack contains only a set of viable prefixes Solution In shift-reduce parsing, the stack contents at any point must form a viable prefix of a right sentential form. A viable prefix is a prefix of a right sentential form that can appear on the stack of a shift-reduce parser. This property ensures that as long as the stack contains a viable prefix, it is possible to continue parsing to reach the start symbol. Therefore, the stack contains only a set of viable prefixes (meaning the content of the stack is always a viable prefix). Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (C) The stack contains only a set of viable prefixes Solution In shift-reduce parsing, the stack contents at any point must form a viable prefix of a right sentential form. A viable prefix is a prefix of a right sentential form that can appear on the stack of a shift-reduce parser. This property ensures that as long as the stack contains a viable prefix, it is possible to continue parsing to reach the start symbol. Therefore, the stack contains only a set of viable prefixes (meaning the content of the stack is always a viable prefix).

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