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I hope we are all well.

I'm having a little hard time understand what negation means in Discrete maths.

Say I have "$2+5=19$" this would be a "Proposition" as its false. So how would I write the "negation". Would I say something like "$2$ plus $5$ does not equal $19$"?

The dictonary definition is: the absence or opposite of something actual or positive.

Thanks, Ben.

Brian Fitzpatrick
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user133149
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    The negation of a proposition is the assertion that the proposition is false. So to do it very formally, the negation of $(2+5=19)$ is $\neg(2+5=19)$, which in more usual language is $(2+5\ne19)$. – David Mar 06 '14 at 01:57
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    BTW, sounds as if that "dictionary definition" came from an ordinary English dictionary... not really a good idea when looking up mathematical terms. Mathematical terms are frequently inspired by ordinary English words, but they never mean exactly the same as ordinary English. – David Mar 06 '14 at 01:59
  • Thanks for that David. Your definiton of negation is better then the one in my text book :). – user133149 Mar 06 '14 at 02:02
  • Yes indeed, I was reading about negation in the text book but I pulled the definition of google as I felt I was faster my bad.. – user133149 Mar 06 '14 at 02:03
  • Google should be OK as long as you make it clear you are looking for mathematical terminology. Though maybe it would be simpler just to start with Mathworld or something like that. – David Mar 06 '14 at 02:05
  • Yer Mathworld looks like the best bet.. – user133149 Mar 06 '14 at 03:08

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