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| 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.
See http://en.wikipedia.org/wiki/Constructivism_(mathematics
\_ 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?
http://en.wikipedia.org/wiki/File:SF_Noe_Valley.png
\_ http://lmgtfy.com/?q=%22san+francisco+neighborhoods%22
\_ http://www.sfarmls.com/docs/areamaps.htm
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
http://en.wikipedia.org/wiki/Neighborhoods_in_San_Francisco |