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Closure relations of a language

  1. Sep 1, 2011 #1
    Hi, I'm having a little trouble understand the idea of closure as so many places seem to describe it differently.

    I'm working on an example problem that states "L* is the closure of language L under which relations?"

    From what I gather, for a language to be closed over a relation, it means that applying that relation to any of its elements results in an element that is also in the language. Is this a correct understanding of the term?

    Applying this knowledge to that question, I would think the answers are:
    Union: L U L is in L*
    Concatenation: LL is in L*
    Kleene Star: L* is in L*

    Is this line of reasoning correct, or am I totally missing the mark? Thanks in advance.
  2. jcsd
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