Alphabets

The alphabet is the set of symbols $\Sigma$.

• English $\Sigma = \{a,b,c,d,...,x,y,z\}$
• ASCII 256 symbols, UNICODE 65536 symbols
• DNA $\Sigma = \{A,C,G,T\}$

Set of all strings: $\Sigma^*$

Size of alphabet: $\vert\Sigma\vert$