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Alternation (formal language theory)

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In formal language theory and pattern matching, alternation is the union of two sets of strings or patterns.

In some programming languages, string concatenation is a binary infix operator, often notated "|". As a pattern, the alternation a|b matches either a or b.

References

  • John E. Hopcroft and Jeffrey D. Ullman, Introduction to Automata Theory, Languages and Computation, Addison-Wesley Publishing, Reading Massachusetts, 1979. ISBN 0-201-02988-X.