Which of the following are regular sets?
$\left\{a^nb^{2m} \mid n \geq 0, m \geq 0 \right\}$
$\left\{a^nb^m \mid n =2m \right\}$
$\left\{a^nb^m \mid n \neq m \right\}$
$\left\{xcy \mid x, y, \in \left\{a, b\right\} ^* \right\}$
Answer is A. Since in option 2 and 3, $n$ is dependent on $m$, therefore a comparison has to be done to evaluate those and hence are not regular. I and IV are clearly regular sets.
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