From CS2800 wiki

The vertical bar [math]\mid [/math] is a general purpose separator. It is used in several places:

  • [math]\{x \mid \href{/cs2800/wiki/index.php/Property}{P} \} [/math] means [math]x [/math] "such that" [math]P [/math] in the context of set comprehensions
  • [math]a \href{/cs2800/wiki/index.php/%5Cmid}{\mid} b [/math] means [math]a [/math] divides [math]b [/math] in the context of number theory
  • [math]\mid [/math] is also used to separate definition rules in inductively defined sets.
  • [math]\href{/cs2800/wiki/index.php/Pr}{Pr}(A \href{/cs2800/wiki/index.php/%5Cmid}{\mid} B) [/math] refers to the conditional probability of [math]A [/math] given [math]B [/math] in the context of probability.

The LaTeX symbol \mid gives a vertical bar with some space on either side.