Berkeley CSUA MOTD:2010:June:29 Tuesday <Wednesday>
Berkeley CSUA MOTD
2010/6/29-7/2 [Uncategorized] UID:53869 Activity:kinda low
6/25    Does anyone actually have a direct proof as to why the Irrational
        Numbers are countable, (one that doesn't start with "assume they
        are countable.."  Thx.
        \_ No, it's not possible.  "Uncountable" means "can't be put into
           one-to-one correspondence with the natural numbers"; the only way
           to prove an impossibility like that is to assume the opposite and
           derive a contradiction.  Mathematicians who reject the idea of
           proof by contradiction also reject the idea of uncountable sets.
           \_ Interesting- i are these folk discredited? I ask because there
              are an awful lot of proofs (including the halting problem,
              not the version that is directly from cantor's diagonal tho)
              that always start out with "assume this is true..."
              \_ I really don't think you'll find a proof that irrational
                 numbers are countable.
        \_ they're not countable.
2010/6/29-7/20 [Reference/BayArea] UID:53870 Activity:nil
6/25    I'm a newbie trying to learn SF neighborhoods, which seem to be
        a colloqial concept not written down anywhere. Is there a map like
        the following (but higher res) that looks like this?
           the only non pretensious map.
           \_ And hence totally useless for learning the traditional names
           \_ would it be pretentious to point out your spelling error?
        \_ enjoy
Berkeley CSUA MOTD:2010:June:29 Tuesday <Wednesday>