Talk:Subadditivity

Vague explanation

 * In other words, if the area under the curve is greater when x and y are two separate curves added together than when x and y are combined and used to define a single curve.

I don't understand this. Fredrik Johansson 22:34, 28 March 2006 (UTC)

Understandable - I don't either - it is not a sentence (there's a 'then' missing somewhere....) Additionally, "The analogue of Fekete's lemma holds for subadditive functions as well." - problem with that is that due to a redirect from Fekete's lemma, that's what this is, so the sentence really says - "The analogue subadditive functions holds for subadditive functions as well." Useful. Can someone fix please???? 131.137.245.200 18:32, 8 May 2006 (UTC)

Completely Incomprehensible
To someone not familiar with the material, this article is utterly incomprehensible. Is it possible to get at least the intro paragraph rewritten so that someone with, say, a basic high school education might acquire a clue as to the subject matter?

* Septegram * Talk * Contributions * 14:32, 5 June 2007 (UTC)

Relation to concavity
Could someone please add a section relating this to concavity? On a quick reading, it seems that, if A  and  B  are fields, then subadditivity implies convexity for positive  f,  and is implied by it for negative  f. LachlanA (talk) 05:18, 31 August 2009 (UTC)

At least two things needed here
First, the definition of subadditivity in the context of measure theory: $$f (A \cup B) \le f(A) + f(B)$$.

Second, it needs to be made plain that the definition as given in this page is valid in the context of semigroups (with the codomain being an ordered semigroup). --WestwoodMatt (talk) 20:23, 23 February 2010 (UTC)

outside economics
The article presently gives the impression that subadditivity is used only in economic theory. I don't have textbooks to hand, but in my experience subadditivity is assumed in most applications of mathematics. In particular, every norm is subadditive. Crasshopper (talk) 22:45, 16 July 2011 (UTC)