Diagonals without tears

Note on a different way to do subsequences, and thereby avoiding some notational difficulty surrounding the diagonal technique for subsequences of subsequences of ….

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Version history

• I have circulated the note privately for a few years, but dusted it off for a class on the foundations of analysis in the fall term of 2011.
• Revised a bit in September 2013.
• Much simplified in January 2021.
• Furhter simplified March/April 2024.