2.7 Sequences of words: token-level regular expressions

• a sequence of words or patterns matches any corresponding sequence in the corpus

  > "on" "and "on|off";
> "in" "any|every" [pos = "NN"];

• modelling of complex word sequences with regular expressions over patterns (i.e. tokens): every [...] expression is treated like a single character (or, more precisely, a character set) in a conventional regular expression
• token-level regular expressions use a subset of the POSIX syntax
• repetition operators:
  ? (0 or 1), * (0 or more), + (1 or more), {$n$} (exactly $n$), {$n$,$m$} ($n\ldots m$)
• grouping with parentheses: (...)
• disjunction operator: | (separates alternatives)
• parentheses delimit scope of disjunction: ( alt$_1$ | alt$_2$ | ... )
• Figure 2 shows simple queries matching prepositional phrases (PPs) in English and German. The query strings are spread over multiple lines to improve readability, but each one has to be entered on a single line in an interactive CQP session.

  Figure 2: Simple queries matching PPs in English and German.