I've scanned a page out of my textbook and highlighted the portion of the proof I don't quite follow. I've been staring at this on and off for a day and for some reason it just doesn't click why the argument shows that R is uniquely determined by W. I see the author is proving an implication and it's converse, but I can't tie it together. I'd appreciate it if anyone could break it down for me a little more. Thanks.(adsbygoogle = window.adsbygoogle || []).push({});

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# Help me understand this proof

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