The colloquial definition is "Useless but impressive and flatters my vanity".

The probabilistic definition is "Observable thing X signals quality A means P(A|X) > P(A)".

The economic definition is "Alice signals P to Bob by X if the net cost of X to Alice is outweighed by the benefits of Bob 'believing' A, and X causes Bob to 'believe' A even when Bob takes in to account that Alice wants him to 'believe' A." (note 'believe' A means 'act as if A were true'.)

The definition of limit: "lim x -> a f(x) = c " means for all epsilon > 0, there exists delta > 0 such that for all x, if 0 < |x-a|<delta then |f(x) - c| < epsilon.

The definition of derivative: f'(x) = lim h -> 0 (f(x+h) - f(x))/h

That is, for all epsilon > 0, there exists delta > 0 such that for all h, if 0 < |h| < delta then |(f(x+h) - f(x))/h - f'(x)| < epsilon.

At no point do we divide by 0. h never takes on the value 0.

I will attend. Is it OK if I bring my boyfriend (User:MixedNuts) along via my iPad?

I'm open to coworking generally.

My ideal coworker is someone who is funny and interested in maths, physics and computer science. My plan would be to read books like Mathematics Form and Function or The Feynman Lectures on Physics and try to summarize / explain the content. For co working where I shut up, I am working on re-implementing MC-AIXI for my honours thesis.

Please contact me if interested, my email is patrick.robotham2@gmail.com my skype nick is grey_fox26

You're accusing me of group selectionism? We might disagree on a point of terminology, but come on, I'm not a completely nutter. Anyway, my point in quoting the wikipedia article is that too much dishonest signalling makes signalling completely pointless ('weakens the integrity of the signalling system'), so for signalling to work you need some way of keeping out the cheats. I'm not proposing anything as daft as "groups without cheats will prosper". Indeed, that's why I was making such a big deal about criterion 4 and cost asymmetry, because the analysis of signalling has to work on an individual basis, including the individuals that might be tempted to cheat.

In my limited imagination, the only way I could think of for keeping out the cheats was having an asymmetric cost structure for honest signalling compared to dishonest signalling. Thus cheating wouldn't be worth it. I now realize this is not the only way. ialdaboth called my attention to Batesian Mimicry, where cheaters are "kept out" simply by the fact that mimics are comparatively rare. Doubtless other ways could be invented.

I think I prefer MagnetoHydroDynamics definition of signalling, and would reserve my criteria for describing costly signalling.

No. I think that because lying is common in human society, a credible signal must be costly to liars.

Well I'm happy to use "costly signalling". I was under the impression that costly signalling was signalling. If it isn't costly, at least for potential fakes, then I'm not sure how it can serve as an explanation for behavior. Why should I signal when the fakes can signal just as easily? What is there to gain? I think at the very least, there has to be some mechanism for keeping out cheats, even if it's rarity. From the wikipedia article on signalling theory:

" If many animals in a group send too many dishonest signals, then their entire signalling system will collapse, leading to much poorer fitness of the group as a whole. Every dishonest signal weakens the integrity of the signalling system, and thus weakens the fitness of the group."

But what am I? Some kind of prescriptivist? Evidently my understanding of the term is a minority, and people far cleverer than I don't use it my way. I'll stick to "costly signal" in future.

“No! I must resolve the muddle” he shouted

The radio said “No, Patrick. You are the muddled one”

And then Patrick was a zombie.

A rube is a sucker, someone easily deceived.The slogan means that potential signalling explanations shouldn't assume that the receiver of the signals is stupid.

Why not? Can't we regard evolutionary signalling as completely analogous to cognitive signalling, just as played by genes over a much longer time scale?