[FOM] constructive Tychonov
Mongre at gmx.de
Wed Nov 28 10:23:15 EST 2007
Is there a constructively provable version of the Tychonov product
theorem? And if there is, exactly what does it say, and what
definition of 'compact' does it use?
I ask because it seems to me that using classical Tychonov with the
usual definition of compactness as open covers having finite
subcovers it's rather straightforward to get the fan theorem (without
going through bar induction) through fans being compact. But I might
be wrong about that (none of the books I've looked at seem to mention
it, and I'm rather vague about just what can be carried over from
classical topology into a constructive setting).
PS I am at present in Berlin, which is why this message is coming
from a gmx address. You can reply either to this address or to my
usual <Robert.Black at nottingham.ac.uk>.
Dept of Philosophy
University of Nottingham
Nottingham NG7 2RD
tel. 0115-951 5845
home tel. 0115-947 5468
[in Berlin: 0(049)30-44 05 69 96]
mobile 0(044)7974 675620
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