A relational symbol denoting precedence or "comes before" in ordered sets and partial orderings.
Examples
Partial ordering relation
a \prec b \prec c
Strict ordering in a poset
\text{For } x,y \in P, \text{ if } x \prec y \text{ then } x \neq y
Comparison of convergence rates
O(n) \prec O(n^2) \prec O(2^n)