# Notation for a subsequence of a sequence

If we have a sequence (an ordered list)

$$S=(s_0,s_1,...,s_n).$$

What is the notation for expressing that $S'$ is a (ordered) subsequence of $S$?

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The indices can be denoted $n_1< n_2<n_3\cdots$; so, $\{ s_{n_i}\}_{i=1}^\infty$. – David Mitra Dec 14 '11 at 9:22
I'd write $S' \subseteq S$. – Peteris Dec 14 '11 at 11:31