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visits member for 4 years, 1 month
seen Jan 27 at 22:54

An amateur general topology researcher.


Dec
5
asked Why “thin groupoids” are not ubiquitous?
Dec
2
comment Another way to express certain filter
See also counter-examples in this thread: groups.google.com/forum/#!topic/sci.math/Plru0S8ePzs
Dec
1
revised Another way to express certain filter
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Dec
1
revised Another way to express certain filter
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Dec
1
revised Another way to express certain filter
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Dec
1
answered Another way to express certain filter
Dec
1
revised Another way to express certain filter
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Dec
1
revised Another way to express certain filter
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Dec
1
revised Another way to express certain filter
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Dec
1
revised Another way to express certain filter
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Dec
1
revised Another way to express certain filter
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Dec
1
comment Another way to express certain filter
The other direction is surprisingly difficult
Dec
1
comment Another way to express certain filter
In one direction: Let $X \in [\mathcal{A}]_{\mathfrak{B}}$. Then $\exists Y' \in \mathcal{A} : X \geq Y'$. Thus if $Y \geq X$ for $Y \in \mathfrak{A}$ then $Y \geq Y'$ and thus $Y \in \mathcal{A}$. So $\forall Y \in \mathfrak{A}: (Y \geq X \Rightarrow Y \in \mathcal{A})$.
Dec
1
revised Another way to express certain filter
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Dec
1
asked Another way to express certain filter
Oct
17
asked Compact frames, an equivalent reformulation
Oct
15
revised Is the locale of filters on an arbitrary lattice compact?
lcoale -> lattice
Oct
15
asked Is the locale of filters on an arbitrary lattice compact?
Oct
15
accepted A filtered poset and a filtered diagram (category)
Oct
14
asked A filtered poset and a filtered diagram (category)