Talk:Cantor-Bernstein-Schröder Theorem/Proof 6

Notation
If you don't like that notation, I suppose I can use $fS$ for the image of $S$ under $f$.... S &amp; F write $f''(S)$, but that seems most bletcherous of all. I like the square brackets; I don't think using round brackets here for two very different things is a good idea. What do you actually want? --Dfeuer (talk) 06:43, 1 April 2013 (UTC)


 * The square bracket notation is used in Kelley 1955. --Dfeuer (talk) 06:51, 1 April 2013 (UTC)


 * Feel free to add the square bracket notation into the Definition:Mapping page in the section discussing notation. Also note that the notation used in S&F is also to be added there.


 * Round brackets are used for exactly the same thing: to define the thing upon which the mapping acts. Hence the notation $f(x)$, whatever $x$ may happen to be (an element or a set of elements) covers everything. If your elements themselves happen to be sets (as is the case when discussing power sets) the headache arising as to whether you are discussing elements or sets and determining which of the notations to use is just too much like hard work.


 * Ultimately it's a matter of house style. Round brackets are used consistently for indicating the image of a mapping, and it is a good idea to keep that convention.


 * As for Kelley using square brackets, note that that was written in 1955 and you are on record as considering works dating back to the 1960s and earlier as less worthy than more modern ones. --prime mover (talk) 08:35, 1 April 2013 (UTC)