Thursday, May 08, 2008

Galois connections

In his classic paper "Adjointness in foundations" (1969), F. William Lawvere writes of 'the familiar Galois connection between sets of axioms and classes of models, for a fixed [signature]'. The idea might be familiar to category theorists, but it isn't easy to find a clear account of what it involves. So, inspired by a talk by Nathan Bowler last term, I've put together a piece on Galois connections to explain. All comments, corrections, suggestions for improvements/additions very welcome. It's part of a planned longer piece about order and ordinals.

[Later] Thanks to Luca Incurvati for catching a daft thinko and a few typos too!

[Later again] I've replaced the previous version with a notationally slightly prettier version.

1 comment:

a cartesian said...

Well, it is a mouse, though a rather cute and furry one.