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| | What are the 'real numbers,' really? |
 | | By a Dedekind cut we mean a pair of sets (A,B), where A and B are nonempty subsets of Q, A is the set of all lower bounds of B (in Q), and B is the set of all upper bounds of A (in Q). |
 | | In particular, the decimal expansions, the Dedekind cuts, and the equivalence classes of Cauchy sequences, though they appear to be entirely different, all turn out to have the same arithmetic and algebraic structure -- they are really the "same" object. |
 | | Let Q be the set of rational numbers; we assume that we already have a good understanding of those. |
| www.cartage.org.lb /en/themes/Sciences/Mathematics/calculus/realnumbers/complete/complete.htm (673 words) |
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