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Regular expressions and finite automata, Context-free grammars and push-down automata, Regular and context-free languages, Pumping lemma, Turing machines and undecidability.

$$\scriptsize{\overset{{\large{\textbf{Mark Distribution in Previous GATE}}}}{\begin{array}{|c|c|c|c|c|c|c|c|}\hline
\textbf{Year}& \textbf{2022} & \textbf{2021-1}&\textbf{2021-2}&\textbf{2020}&\textbf{2019}&\textbf{2018}&\textbf{2017-1}&\textbf{2017-2}&\textbf{2016-1}&\textbf{2016-2}&\textbf{Minimum}&\textbf{Average}&\textbf{Maximum}
\\\hline\textbf{1 Mark Count} & 2 &2&3&3&2&2&2&3&3&3&2&2.5&3
\\\hline\textbf{2 Marks Count} & 3 &3&4&3&3&3&5&3&3&3&3&3.3&5
\\\hline\textbf{Total Marks} & 8 &8&11&9&8&8&12&9&9&9&\bf{8}&\bf{9.1}&\bf{12}\\\hline
\end{array}}}$$

Previous GATE Questions in Theory of Computation

36 votes
6 answers
101
29 votes
5 answers
108
Give a regular expression for the set of binary strings where every $0$ is immediately followed by exactly $k$ $1$'s and preceded by at least $k$ $1$’s ($k$ is a fixed...
17 votes
2 answers
109
23 votes
6 answers
112
If $L_1$ and $L_2$ are context free languages and $R$ a regular set, one of the languages below is not necessarily a context free language. Which one?$L_1.L_2$$L_1 \cap L...
30 votes
6 answers
115
26 votes
5 answers
117
41 votes
5 answers
118
A finite state machine with the following state table has a single input $x$ and a single out $z$.$$\begin{array}{|c|ll|}\hline\textbf{present state} & \qquad \textbf{nex...
32 votes
8 answers
119