Recent questions tagged context-free-language

Consider the CFG$$\begin{aligned}S &\to VS \mid cT \\T &\to VT \mid cU \\U &\to \epsilon \mid VU \\V &\to a \mid b\end{aligned} $$Which language is generated by this gram...

Which CFG generates the language $L = \{a^m b^n \mid 2m=n \text{ or } m=2n\}$?$S \to aSbb \mid aaSb \mid \epsilon$ $S \to X \mid Y$$X \to aXbb \mid \epsilon$$Y \to aaYb \...

Which of the following languages cannot be accepted by push down automata?$\mathrm{L}=\left\{\mathrm{a}^\mathrm{n} \mathrm{b}^{n} c^\mathrm{n}: \mathrm{n} \geq 0\right\}$...

Let $\Sigma=\{a, b, c, d\}$ and let $L=\left\{a^{i} b^{j} c^{k} d^{\ell} \mid i, j, k, \ell \geq 0\right\}$.Which of the following constraints ensure(s) that the language...

Consider the following context-free grammar $G$.\[\begin{array}{l}S \rightarrow a b a A B A b b a \\A \rightarrow a a B B A b \mid b B a b a a \\B \rightarrow a B b \mid ...

Consider the following CFG $G$ over $\Sigma = \{\mathbf{a},\mathbf{b},\mathbf{c},\mathbf{d}\}$:\[\begin{array}{rcl}S & \rightarrow & S\mathbf{a} \;\mid\; \mathbf{d}T \\T ...

Which of the following are context free language?$\left\{\mathrm{w}^{\mathrm{i}} \mathrm{x}^{\mathrm{j}} \mathrm{y}^{\mathrm{k}} \mathrm{z}^{l} \mid \mathrm{i}+\mathrm{k}...

Let $\text{A}=\{a, b\}$ and $\text{L}=\text{A}^{*}$. Let $x=\left\{a^{n} b^{n}, n>0\right\}$. The languages $\text{L} \cup \text{X}$ and $\text{X}$ are respectively :Not ...

Consider the following two languages over the alphabet $\{a, b, c\}$, where $m$ and $n$ are natural numbers.$$\begin{aligned} L_{1} & =\left\{a^{m} b^{m} c^{m+n} \mid m, ...

Can anyone help me to understand what's wrong with my solution??

Let $\Sigma=\{a, b\}$ be an alphabet. A palindrome is a word which reads the same when read from left-to-right, or from right-to-left. For example, the words $a b b a, a ...

Let $L$ be a regular language, and let $n=10$. Which of the following statements is true?$L \cup\left\{a^{n} b^{n}\right\}$ is regular$L \cup\left\{a^{n} b^{n}\right\}$ i...

Which f the following statements is FALSE?The intersection of a regular language and a context-free language is context=freeThe intersection of a regular language and con...

Is this language regular or not?xww^R | x,w E (a,b)*