arithmetic language

[desh]

We say "two plus three", but we say "add two and three", and that's "addition". And some of us might've laughed under our breath in middle school at the kids in math class who used "plus" as a verb. Similarly, "two minus three" but "subtract three from two" for "subtraction", "two times three" but "multiply two by/and three" for "multiplication", and so on.

When you're talking sets, what do you do instead? I guess "B intersect C" and "intersect B and C" for "intersection", but what about union? "Then you union B and C" sounds almost as wrong as "Then you times 2 and 3".

Comments

As I see it.

[captainjew.livejournal.com]

The problem is that addition, subtraction, et al. are operations to be performed where as union and intersection are subsets rather than something to do.

Re: As I see it.

[desh]

I disagree. You don't think these are analogous, if not in the sorts of answers they produce, then at least in whether they're "something to do" or not?

a * b = c
A ∩ B = C

or, in a procedural sense:

let c = a * b
let C = A ∩ B

Re: As I see it.

[captainjew.livejournal.com]

But with multiplication you are solving something. Any solutions involving union or intersection are achieved through other operations.

Re: As I see it.

[desh]

I don't know; I definitely feel like I'm solving things. Here, let me give you a fake example from work:

I need to calculate the set of all the people who don't have to pay taxes. The law says that you don't have to pay taxes iff you have a dog and red is your favorite color. I already have the set of all dog owners and the set of all people with a given favorite color. So I want:

No_taxes = Dog_owners ∩ Favorite_color(red)

How is that any different conceptually than this?

Tax_owed = Gross_income - Deductions