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Single Idea 14143

[filed under theme 6. Mathematics / A. Nature of Mathematics / 5. The Infinite / h. Ordinal infinity ]

Full Idea

The ordinal representing the whole series must be different from what represents a segment of itself, with no immediate predecessor, since the series has no last term. ω names the class progression, or generating relation of series of this class.

Gist of Idea

ω names the whole series, or the generating relation of the series of ordinal numbers

Source

Bertrand Russell (The Principles of Mathematics [1903], §291)

Book Ref

Russell,Bertrand: 'Principles of Mathematics' [Routledge 1992], p.313


A Reaction

He is paraphrasing Cantor's original account of ω.


The 9 ideas with the same theme [infinity as an unending ordered series]:

Cantor's theory concerns collections which can be counted, using the ordinals [Cantor, by Lavine]
Cantor extended ordinals into the transfinite, and they can thus measure infinite cardinalities [Cantor, by Maddy]
The number of natural numbers is not a natural number [Frege, by George/Velleman]
ω names the whole series, or the generating relation of the series of ordinal numbers [Russell]
Ordinals are basic to Cantor's transfinite, to count the sets [Lavine]
Paradox: the class of all ordinals is well-ordered, so must have an ordinal as type - giving a bigger ordinal [Lavine]
Raising omega to successive powers of omega reveal an infinity of infinities [Friend]
The first limit ordinal is omega (greater, but without predecessor), and the second is twice-omega [Friend]
Transfinite ordinals are needed in proof theory, and for recursive functions and computability [Hossack]