i have a statement: Let R be a binary relation on a set X. R is reflexive if (x, x) belongs to R for each x belongs to X.(adsbygoogle = window.adsbygoogle || []).push({});

what is a binary relation? what does the (x, x) mean? how can x be both the input and output? and finally...i see the book i have has IdX where X is a subscript. and sometimes replaced with the notation for real numbers. what does the Id. mean?

thanks,

barneygumble742

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# Let R be a binary relation on a set X

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