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 Post subject: QuantifiersPosted: Fri, 11 Sep 2009 01:43:21 UTC
 S.O.S. Oldtimer

Joined: Fri, 18 Jul 2008 01:21:42 UTC
Posts: 147
Location: California, USA
Could someone show me how to prove the following?

(not for some x)P(x) is equivalent to ((for all x)(not P(x))

Thank you so much

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Susan

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 Post subject: Re: QuantifiersPosted: Fri, 11 Sep 2009 01:50:38 UTC
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Joined: Mon, 29 Dec 2008 17:49:32 UTC
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Susan123456 wrote:
Could someone show me how to prove the following?

(not for some x)P(x) is equivalent to ((for all x)(not P(x))

Thank you so much

"(not for some x)P(x)" is:
"(for all x)(not P(x))" is:

By definition, is a shorthand for , and now apply double negation...

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