In Spivak's Calculus, he provides a """rigorous construction""" of the ordered pair

In Spivak's Calculus, he provides a """rigorous construction""" of the ordered pair.

To do so, he defines (a,b) as {{a},{a,b}}.

Can one of you explain how this is significant or rigorous. The definition and accompanying theorem seem arbitrary to me.

Set inclusion/difference gives the ordering.

Could you explain this further? I'm completely lost.

>Can one of you explain how this is significant or rigorous.
He is showing that if you have 2 ordered pairs which are equal to each other they are made up out of the same members, it is written right there on the page.
It is obviously important to prove this, else the definition wouldn't make much sense.

>rigorous
It obviously is rigorous, there are no uncertainties and the definition is clear and unambiguous.

>significant
You need ordered pairs to construct the rational numbers and other things but the necessity for such a thing should be obvious.

The fuck? What's so hard to get about [math] \{a\} \subset \{a,b\} [/math]

One more hint: [math] \{a,b\} \eq \{b,a\} [/math].
You should figure the rest out by yourself (if you can't, I suggest you study something else.)

can this be extended to triplets and n-tuples
with (a,b,c)->{{a},{a,b},{a,b,c}}
(a1,a2,...,an)->{{a1},{a1,a2}...,{a1,a2,...,an}}
using induction on the same argument?

No, it's rigorous in the sense that it is set theoretical, i.e. it is based on more general primitive notions.

What do you think?

I think that you're a bad teacher.