User:Jshflynn/Definition:i-th letter
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Definition
Let $\Sigma$ be an alphabet and let $x$ be a word over $\Sigma$.
Then the $i$-th letter of $x$ is the $i$-th term of $x$ when interpreted as a sequence over $\Sigma$.
It is denoted $x_i$.
Example
Example 1
Given the alphabet $\{$ a, 7, d, t, g $\}$ and the word $x = \langle$ g, t, d, g $\rangle$.
Then $x_2 =$ t.