送交者: fuzzify 于 2007-01-09, 16:42:07:

回答: by definition, every element in a countable infinite set has 由 steven 于 2007-01-09, 16:30:22:

• if the set is rational, it is countable. If it is a set of real, it is not. (无内容) - steven (0 bytes) 2007-01-09, 16:43:03 (119498)
  • 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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