Definition talk:Topology Generated by Synthetic Sub-Basis

I understand your use of $:=$ meaning (I think) "is defined as", but what is $=:$? --Matt Westwood 07:34, 26 January 2010 (UTC)


 * As far as i know, $:$ separates a name from the thing it is defined to refer to, and $:$ is followed by how the name refers to the object. So $a := b$ means that whenever I say $a$, I mean the same object as if I had said $b$. I could also say $a :\Leftrightarrow b$, this would mean that whenever I say $a$, I refer to something that is equivalent to $b$ (whatever that means in the surrounding context). Same goes for things like $f : X \rightarrow Y$ and so on. I'm not sure if this is standard in any way (it's just how I learned it). If there's some established standard around here, just let me know.


 * And switching it around like $y =: x$ is just the same as saying $x := y$. Sometimes it's more readable: Whereas $x := y$ is like "I will use the name $x$ for the following concept ($y$)", $y =: x$ is more like "Thus we arrive at the following concept ($y$), which I'll call $x$". But it's a matter of personal taste. Again, if there's already a standard on how things are done, let me know. If not it might be a good idea to think about such a standard. --Florian Brucker 11:35, 29 January 2010 (UTC)