John_Maxwell_IV comments on New Year's Predictions Thread - Less Wrong

18 Post author: MichaelVassar 30 December 2009 09:39PM

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Comment author: John_Maxwell_IV 12 January 2010 06:05:53AM *  0 points [-]

You're demanding a certain amount of strictness that is itself short of perfect strictness.

Actually, I'm fine with people speaking vaguely, I just don't want to see terminology misused.

There's no such thing as an "arbitrarily small number".

"Through adding zeroes between the decimal point and the 7 in the string '.7', the number we are representing can be made arbitrarily small." Is this a misuse of the word "arbitrarily"?

In particular, a given epsilon need not be "negligible". Really, to conform to the strict mathematical usage, one shouldn't say "epsilon" without first saying "For every".

The important think about an epsilon in a mathematical proof is, conventionally, that it can be made arbitrarily small. This is a human interpretation I am adding on to the proof itself. If the important thing about a variable in a proof was that the variable could become arbitrarily large, my guess is that a variable other than epsilon would not be used.

Comment author: Tyrrell_McAllister 12 January 2010 03:22:36PM 1 point [-]

"Through adding zeroes between the decimal point and the 7 in the string '.7', the number we are representing can be made arbitrarily small." Is this a misuse of the word "arbitrarily"?

Your usage is fine, so long as it's clear that "arbitrarily small" is a feature of the set from which you are choosing numbers, or of the process by which you are constructing numbers, and not of any particular number in that set. This is clear with the context that you give above. It wasn't as clear to me when you wrote that "epsilon is (conventionally) an arbitrarily small number".