math logic

sara15

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Joined
Feb 4, 2011
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can any one give me a first-order sentence that says there exist exactly three elements. Please explain it to me.
Thanks
 
You want to say the following: "there exist x, y and z such that none of these three are equal, and for all w, w is equal to one of these." Now see if you can write that as a first order sentence.
 
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