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To what subject terms SUP ,INF come from?

  1. Nov 19, 2008 #1
    what type of lectures should i look for in order to understand this
    i am taking a calculus course which involve them
  2. jcsd
  3. Nov 19, 2008 #2
    Sup and inf stand for supremum and infimum respectively. Sometimes they are called by the names least upper bound and greatest lower bound, respectively.

    In a sense, they act very similar to the minimum and maximum of a set of real numbers. In fact, whenever a set has a minimum, the infimum is the same as the minimum (and similarly for maximum and supremum).

    However, some sets do not have minimums, but they DO have infimums. The set of positive reals, for example, has no minimum, but the infimum is 0.

    (Still other sets have neither, such as the set of reals).

    Infimums and supremums are very closely related to the ideas of a limit.

    These concepts are something you might learn about in set theory, order theory, or analysis.
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