Category Archives: Uncategorized

Locales, sublocales II: sieves

Last time, I promised you we would explore another way of defining sublocales.  We shall again use the naive approach that consists in imagining how we would encode subspaces of a T0 topological space X by looking at open subsets … Continue reading

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Locales, sublocales I

Stone duality leads naturally to the idea of locale theory.  Quickly said, the idea is that, instead of reasoning with topological spaces, we reason with frames.  The two concepts are not completely interchangeable, but the O ⊣ pt adjunction shows … Continue reading

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Ideal Models III: Quasi-ideal domains

I am a bit stubborn. In my first post on ideal domains, I thought I would be able to extend Keye Martin’s result from metric to quasi-metric spaces. I have said I had failed, but now I think I have … Continue reading

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Remainders, bqos, and quasi-Polish spaces again

In my first post on ideal domains, I thought I would be able to extend Keye Martin’s result from metric to quasi-metric spaces. That was more complicated than what I had thought. Along my journey, I (re)discovered a few results, … Continue reading

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Ideal models II

Last time, we have seen that every completely metrizable space X has an ideal model, that is, that X can be embedded into an ideal domain Y in such a way that we can equate X with the subspace of … Continue reading

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Happy New Year 2016!

I had not posted a crossword puzzle for a long time, so here is one at last: in pdf format, or in AcrossLite format, as usual.  Happy New Year!

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Ideal domains I

A few months ago, Keye Martin drew my attention to his results on so-called ideal models of spaces [1].  Ideal domains are incredibly specific dcpos: they are defined as dcpos where each non-finite element is maximal.  Despite this, Keye Martin … Continue reading

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Domains XII

In my last post, I said I would have trouble finding time to write anything up in August, and sadly, this came out true. Late August, I went to the Domains XII conference, and it may be a good idea if I … Continue reading

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Adjoint Functor Theorems: GAFT and SAFT

You have probably sweated a lot at trying to understand the constructions of Part IV.  They rest on a lot of topology and domain theory.  Perhaps surprisingly (if you do not know it already), they are completely generic, and work in … Continue reading

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Powerdomains and hyperspaces IV: theories

Last time, we concluded with a mysterious observation.  There is a theory, that of unital inflationary topological semi-lattices, which plays a fundamental role in the study of the Hoare powerspace.  On the one hand, H(X) is the free sober such thing.  On the … Continue reading

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