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Filters in Topology - Page 2

Blogs > Plexa
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Wonders
Profile Blog Joined September 2006
Australia753 Posts
December 17 2010 06:33 GMT
#21
Is this written for a "layman" with some experience in mathematics but not convergence spaces in particular? Presumably it is, since in your own words it's all the baby stuff - background information. If so then perhaps you could motivate the definition of a filter a bit more, maybe by first looking at an example where sequences aren't sufficient to define continuity, or by defining a net first. It's just a suggestion, since after reading the first few pages I still have no idea why on earth you'd ever want a filter.
Plexa
Profile Blog Joined October 2005
Aotearoa39261 Posts
December 17 2010 09:15 GMT
#22
On December 17 2010 12:59 Klockan3 wrote:
F.3 is wrong, it should be "then" and not "and".

Thanks
On December 17 2010 15:33 Wonders wrote:
Is this written for a "layman" with some experience in mathematics but not convergence spaces in particular? Presumably it is, since in your own words it's all the baby stuff - background information. If so then perhaps you could motivate the definition of a filter a bit more, maybe by first looking at an example where sequences aren't sufficient to define continuity, or by defining a net first. It's just a suggestion, since after reading the first few pages I still have no idea why on earth you'd ever want a filter.

Either nets or filters suffice as a generalisation (and indeed, they're equivalent). I think including a motivating example at the beginning would be a good idea though (although imo the rewards for dealing with compactness using filters is justification enough :D!).
Administrator~ Spirit will set you free ~
Wonders
Profile Blog Joined September 2006
Australia753 Posts
December 17 2010 10:24 GMT
#23
My understanding was that filters are even more general than nets though. Nets seem to be easily motivated by the need to define topological properties in terms of sequences. An analogous motivation for filters would be very useful to someone who's never heard of them before.
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