if the set is rational, it is countable. If it is a set of real, it is not.
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送交者: steven 于 2007-01-09, 16:43:03:
回答: is [0,1] countable then? :) 由 fuzzify 于 2007-01-09, 16:42:07:
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- Exactly. In real world, how can you ignore irrational ones (无内容) - fuzzify (0 bytes) 2007-01-09, 16:49:42 (119500)
- that's what I was trying to say: there is no 1-1 mapping between - fuzzify (26 bytes) 2007-01-09, 23:41:15 (119554)
- to be exact, the function should 1-1 or bidirectional. (无内容) - 匆匆过客 (0 bytes) 2007-01-09, 22:35:41 (119551)
- you already said integers is countable, but real numbers are not. - fuzzify (68 bytes) 2007-01-09, 21:44:44 (119543)
- typo: the cardinal of Real is Beth one. (无内容) - steven (0 bytes) 2007-01-09, 18:26:28 (119515)
- The real number, which is called continuum isn't a countable set. - steven (222 bytes) 2007-01-09, 17:58:25 (119510)
- ok. Anyway, there is no such mapping function between - fuzzify (32 bytes) 2007-01-09, 17:31:01 (119505)
- then again, in the real world, things are actually quantized. :) - steven (77 bytes) 2007-01-09, 17:10:19 (119503)
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