Talk:Disjoint sets

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Mathematics rating:	Stub Class	Mid Priority	Field: Foundations, logic, and set theory
Please update this rating as the article progresses, or if the rating is inaccurate. Click to show/hide comments. Please add to or update the comments to suggest improvements to the article. Geometry guy 16:24, 10 June 2007 (UTC)

Contents 1 Set Theory 2 Small error

[edit] Set Theory

Set theory is an esoteric branch of mathematics that deals with the possible axioms of set theory and the impact that these have on the other brances of math that use sets. The vast majority of the times that sets (and the notion of disjoint sets) are used in math, it is not set theory. In fact, I can't recall that any of the big issues of set theory have to do with disjointness anyways, so talk of disjoint sets is, if anything, a clue that you're dealing with some other branch of math. I certainly agree that it was right to mention context, however. — Toby 08:42 Sep 19, 2002 (UTC)

Being a computer science student, I had no idea that set theory is considered to be "esoteric"; it is in fact one of the first things new students learn at my university. But this is enough context for me, so I don't really care. Jeronimo

there are branches of maths that aren't esoteric? ;-) -- Tarquin

I'm not sure that what you learn in the class called "Set Theory" is what a set theorist would consider set theory. There is some actual set theory in the "Set Theory" class at my school, but it barely scratches the surface and isn't the real focus of the class, which is instead learning to manipulate algebraic symbols for sets — and that's what this article is about too.

However, giving further thought, I realise that one could make the same charge about classes called "Algebra" or "Math Analysis" (the new name for "Pre-Calculus" in American high schools), or even "Arithmetic". We mathematicians make clear what we mean by these by saying things like "high school algebra" or "elementary arithmetic". We could say that this is part of "naïve set theory". In fact, I've been thinking that we should rename the Wikipedia article Basic set theory (a phrase that I've never heard) as Naive set theory (and we could even rename Set theory as Axiomatic set theory if we want to be especially precise).

Well, anyway. — Toby 22:57 Sep 19, 2002 (UTC)

[edit] Small error

"If {A_i} is a pairwise disjoint collection, then clearly its intersection is empty." This is not true, as the collection might consist of exactly one element. Wasseralm 18:35, 4 March 2007 (UTC)