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- Jun 22, 2012

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I am currently focused on understanding Chapter 1: Sets ... and in particular Section 1.4 Ordinals ...

I need some help in fully understanding Theorem 1.4.4 ...

Theorem 1.4.4 reads as follows:

In the above proof by Searcoid we read the following:

"... ... Now, for each \(\displaystyle \gamma \in \beta\) , we have \(\displaystyle \gamma \in \alpha\) by 1.4.2, and the minimality with respect to \(\displaystyle \in\) of \(\displaystyle \beta\) in \(\displaystyle \alpha \text{\\} x\) ensures that \(\displaystyle \gamma \in x\). ... ...

Ca someone please show formally and rigorously that the minimality with respect to \(\displaystyle \in\) of \(\displaystyle \beta\) in \(\displaystyle \alpha \text{\\} x\) ensures that \(\displaystyle \gamma \in x\). ... ...

Help will be appreciated ...

Peter

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It may help MHB readers of the above post to have access to the start of Searcoid's section on the ordinals (including Theorem 1.4.2 ... ) ... so I am providing the same ... as follows:

It may also help MHB readers to have access to Searcoid's definition of a well order ... so I am providing the text of Searcoid's Definition 1.3.10 ... as follows:

Hope that helps ...

Peter