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Math Help - Nested Quantifiers

  1. #1
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    Question Nested Quantifiers

    I was confused with g).

    Thx for comming.
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  2. #2
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    \exists x\,\forall y\, (y\ne x \Rightarrow M(x,y)).
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  3. #3
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    Thank U very much.
    But
    .

    what's different with My anwser :
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  4. #4
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    Quote Originally Posted by repcvt View Post
    what's different with My anwser :

    The statement \exists x\,\forall y\, (M(x,y)\wedge y\ne x) means that there is a student (x) who has emailed everyone in the class and who is different from everyone in the class. But that would mean in particular that x is different from himself/herself. Obviously that's not possible.

    You could have given the alternative solution \exists x\,\forall y\, ((y= x) \vee M(x,y)) (meaning that either x=y or x has emailed y).
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  5. #5
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    Quote Originally Posted by Opalg View Post
    The statement \exists x\,\forall y\, (M(x,y)\wedge y\ne x) means that there is a student (x) who has emailed everyone in the class and who is different from everyone in the class. But that would mean in particular that x is different from himself/herself. Obviously that's not possible.

    You could have given the alternative solution \exists x\,\forall y\, ((y= x) \vee M(x,y)) (meaning that either x=y or x has emailed y).

    Understand it now.Thank U very much.BTW,How did U make that so good express like that



    I mean how edit that image like that.look my express,that is so bad.I drawed it handly.
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  6. #6
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    Quote Originally Posted by repcvt View Post
    How did U make that so good express like that



    I mean how edit that image like that.
    http://www.mathhelpforum.com/math-he...-tutorial.html
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