TR-7 PRG Technical Report TR-6-00

Programming Research Group Technical Report TR-7-00

On the antisymmetry of Galois embedding

J. Burghardt, F. Kammüller and J.W. Sanders

October 2000, 9 pp.

Abstract

A Galois connection is a `natural' way of relating two partially-ordered spaces (for example semantic models of different expressive power). The most common form of Galois connection, which reflects one model being finer than the other, is that of a Galois embedding. This letter shows a published claim, `two partially-ordered spaces related by a Galois embedding in each direction are isomorphic', to be false in general but true in the finite case. The proof we give provides an application of a `disjoint from' calculus.
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