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- Question in respect of the proof that compact subsets of R are necessarily closed and bounded ... issue of an open cover with no finite subcover ...
I am reading Houshang H. Sohrab's book: "Basic Real Analysis" (Second Edition).
I am focused on Chapter 4: Topology of R and Continuity ... ...
I need help in order to fully understand the proof of Proposition 4.1.8 ...Proposition 4.1.8 and its proof read as follows:
In the above proof by Sohrab we read the following:
" ... ... If, to get a contradiction, we assume that ##\xi \notin K## is a limit point of ##K##, then the open cover ##\{ ( - \infty, \xi - 1/n ) \cup ( \xi + 1/n, \infty ) \}_{ n \in \mathbb{N} }## has no finite subcover ... ... "
My question is as follows:
How would we demonstrate rigorously that the open cover ##\{ ( - \infty, \xi - 1/n) \cup ( \xi + 1/n, \infty ) \}_{ n \in \mathbb{N} }## has no finite subcover ... ...?
Help will be appreciated ...
Peter
=======================================================================================It may help readers of the above post to have access to Sohrab's definition of a limit point ... so I am providing the relevant text ... as follows ...
Hope that helps ...
Peter
I am focused on Chapter 4: Topology of R and Continuity ... ...
I need help in order to fully understand the proof of Proposition 4.1.8 ...Proposition 4.1.8 and its proof read as follows:
In the above proof by Sohrab we read the following:
" ... ... If, to get a contradiction, we assume that ##\xi \notin K## is a limit point of ##K##, then the open cover ##\{ ( - \infty, \xi - 1/n ) \cup ( \xi + 1/n, \infty ) \}_{ n \in \mathbb{N} }## has no finite subcover ... ... "
My question is as follows:
How would we demonstrate rigorously that the open cover ##\{ ( - \infty, \xi - 1/n) \cup ( \xi + 1/n, \infty ) \}_{ n \in \mathbb{N} }## has no finite subcover ... ...?
Help will be appreciated ...
Peter
=======================================================================================It may help readers of the above post to have access to Sohrab's definition of a limit point ... so I am providing the relevant text ... as follows ...
Hope that helps ...
Peter