Theory of Computation · Regular Expressions and Finite Automata
Official IIT answer key · IIT Kanpur · Audited Aug 2026
GATE CSE 2015 Set 1 Q52 · NAT · 2 marks

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Topic notes
The topic of Regular Expressions and Finite Automata is one of the highest-weight core areas in GATE CS Theory of Computation. Questions test minimal DFA state counting under modulo/substring constraints, state equivalence and minimization, regular expression derivation from transition graphs (and vice versa), NFA-to-DFA powerset bounds (2n), and language membership/closure properties. The distribution balances 1-mark foundational conceptual checks with 2-mark state-tracing and counting problems.
Full Regular Expressions and Finite Automata guide →All 41 questions on Regular Expressions and Finite Automata →
Consider the DFAs M and N given above. The number of states in a minimal DFA that accepts the language L(M) L(N) is …
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