languages

Consider the following sets : S1. Set of all recursively enumerable languages over the alphabet $\{0,1\}$ S2. Set of all syntactically valid C programs S3. Set of all languages ove...

Let $$\sum \, $$ be a finite non - empty alphabet and let $${2^{\sum {{}^ * } }}$$ be the power set of $$\sum {{}^ * .\,} $$ Which one of the following is TRUE ?

$$\sum { = \left\{ {a,b} \right\},\,\,} $$ which one of the following sets is not countable.