Friday 25 February 2011

Definitions of set, sub-set, proper sub-set

SETS: A collection of well defined objects is called a set. It is always represented by a capital letter. A set can be represented by
(i) a venn diagram (ii) an equation or an expression or (iii) verbal expression.
  1. A set can be represented by a closed figure like a circle, a triangle etc. Such a representation is called a Venn diagram.
    The points inside this figure represent the members of the set.
  2. If a set A contains objects having property P in common, we write the
    set A ≡ {x / x has property P}
    If B ≡{3, 4} ≡ {x / x ∈ W and x2 - 7x + 12 = 0}.
    If C ≡ {7, 8, 9, 10, ...} ≡ {x / x ∈ W, x ≥ 7.
    This is also known as the set builder notation.
  3. If a set A is set of all vowels in English alphabets, then A ≡ {a, e, i, o, u}.
    A ≡ {set of all vowels in English alphabets}

    This is verbally expressed

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