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| | [No title] (Site not responding. Last check: 2007-10-13) |
 | | The underlying set functor on Top\op takes a space to the set of all pairs (U,A) where U is open and A is an arbitrary subset of U. The frame operations are the usual, while (U,A)' = (U,U - A). |
 | | The first condition is sufficient to ensure that, for each topological space X, the canonical counit map X -----> B^Top(X,B) is an injection, and the second ensures that it is the embedding of a subspace. |
 | | This particular algebraic theory to which you refer is perhaps exactly that arising from the space B having three points, one of which is closed, with open complement (containing the other two points) as the only non-trivial open. |
| www.mta.ca /~cat-dist/catlist/1999/topop (385 words) |
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