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Indicator function

  1. Nov 22, 2014 #1
    Hi Everyone,
    So here is a prove given in book by Corbae S tinchcombe Zemam so can someone clear this line of prove to me that
    1AU(B∩C)=1A.(1 B +1C -1B .1C )

    I don't get it please help
    thanks in advance
  2. jcsd
  3. Nov 23, 2014 #2
    Seems to me that it should be $$1_{A\cap(B\cup C)}=1_A\cdot(1_B+1_C-1_B\cdot1_C)$$ which follows from $$1_{X\cap Y}=1_X\cdot 1_Y$$ and $$1_{X\cup Y}=1_X+1_Y-1_X\cdot1_Y$$
  4. Nov 23, 2014 #3
    that means it must be misprint or something like that because union is between A and (B intersection C) and you have taken union in B and C where there was a intersection given
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