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for unions of two regular languages that are themselves defined by finite automata is central to the equivalence between regular languages defined by automata and by regular expressions.
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under alternation, meaning that the alternation of two regular languages is again regular. In implementations of
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Introducing
Regular Expressions: Unraveling Regular Expressions, Step-by-Step
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language and some other languages. In formal language theory, alternation is
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Other classes of languages that are closed under alternation include
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may instead be used for this purpose. The ability to construct
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Introduction to
Automata Theory, Languages and Computation
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108:. Jones & Bartlett Learning. pp. 100–101.
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36:of two patterns describing sets of strings.
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159:"Alternation with The Vertical Bar"
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
