JoshuaZ comments on Proofs, Implications, and Models - Less Wrong

58 Post author: Eliezer_Yudkowsky 30 October 2012 01:02PM

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Comment author: JoshuaZ 10 November 2012 07:20:51PM 2 points [-]

sqrt(x^2)=5 or -5, along with an infinite number of complex values

No. Even in the complex plane there are only two possible square roots. Moreover, if one wants to sqrt to be a function one needs a convention, hence we definite sqrt to be the non-negative square root when it exists.