The numbers $$1, 2, 4, 8, $$ ...... $${2^n},$$ ............. written in binary.

The numbers $$1, 2, 4, ..... $$ $${2^n},$$ $$.....$$ written in unary.

The set of binary strings in which the numbers of zeros is the same as the numbers of ones.

The set $$\left\{ {1,101,11011,1110111,...} \right\}.$$

$${110^ * }\,\,\left( {0 + 1} \right)$$

$$\,1\,{\left( {0 + 1} \right)^ * }101$$

$${\left( {10} \right)^ * }\,{\left( {01} \right)^ * }\,{\left( {00 + 11} \right)^ * }$$

$${\left( {00 + {{\left( {11} \right)}^ * }0} \right)^ * }$$

Set of all strings over $$\sum {} $$

Set of all languages over $$\sum {} $$

Set of all regular languages over $$\sum {} $$

Set of all languages over $$\sum {} $$ accepted by Turing Machines.

$$L = \,\,\,\left\{ {\left. x \right|\,\,\,x} \right.$$ has an equal number of $$a's$$ and $$\,\left. {b's} \right\}$$ is regular

$$L = \left\{ {{a^n}{b^n}\left| {n \ge 1} \right.} \right\}$$ is regular

$$L = \,\,\,\left\{ {\left. x \right|\,\,\,x} \right.\,$$ has more $$a's$$ than $$\left. {b's} \right\}$$ is regular

$$L = \left\{ {{a^m}{b^n}\left| {m \ge 1,\,n \ge 1} \right.} \right\}$$ is regular