Talk:Cauchy's functional equation

Other solutions
The last section is titled "Proof of the existence of other solutions" Without the final line it merely constructs a family of solutions, without showing that they are different from the obvious linear solutions. I have therefore restored the last line. EdwardLockhart 16:24, 9 February 2007 (UTC)

Hilbert's fifth problem?
The lead says without further explanation "The fifth problem on Hilbert's list is a generalisation of this equation". Apart from the fact that it is curious for a problem to be a generalisation of an equation, this strikes me as a far-fetched claim. Certainly Hilbert's fifth problem has to do with continuous (group) operations. Can somebody explain this? Marc van Leeuwen (talk) 13:23, 4 December 2011 (UTC)

Extension to higher and infinite dimensions?
What do additive functions from one real vector space to another have to look like? It seems likely that they must be quite horrible when both spaces are finite-dimensional, but is that also true if one or both are infinite-dimensional spaces? Dfeuer (talk) 18:17, 29 October 2012 (UTC)