Why: Because the textbooks can be wrong.

If

n+w = w

Then it is aMUSTthat

w+n =w

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- February 17th 2009, 09:25 AM #1

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## n+w is w, bt w+n is not w. Why?

cannot comprehend this from my text book. How to understand this?

Consider the order types w and n. It is easy to see that n+w=w. In fact, if finitely many terms are written to the left of the sequence 1,2,...,k,..., we again get a set of the same type(why?). On the other hand, the order type w + n, i.e., the order type of the set {1,2,...,k,...,a1,a2,...,an} is obviously(?) not equal to w.

- February 17th 2009, 09:30 AM #2

- February 17th 2009, 09:44 AM #3

- February 17th 2009, 09:51 AM #4

- February 17th 2009, 11:56 AM #5

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- February 17th 2009, 11:59 AM #6

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