The set R is a relation on A, by Definition 11.1. Since (1,1) 2 R, we have
1R1. Similarly 2R1 and 2R2, and so on. However, notice that (for example)
(3,4) Ý R, so 36R4. Observe that R is the familiar relation ¸ for the set A.
Chapter 1 proclaimed that all of mathematics can be described with
sets. Just look at how successful this program has been! The greaterthan-
or-equal-to relation is now a set R. (We might even express this in
the rather cryptic form ¸Æ R.)