## May 27, 2008

### Cahiers Free Online!

#### Posted by John Baez

Yay! The journal founded by the famous geometer and category theorist Charles Ehresmann and ably continued by his wife Andrée is now free online! It began in 1957 as the Séminaire Ehresmann, and in 1966 it became Cahiers de Topologie et Géométrie Différentielle. You can read a wee bit of its history here.

You can get all the old issues on the NUMDAM website:

From now on, papers will become electronically less than 2 years after publication in print.

Never bought out by the big publishing conglomerates, Cahiers has always had a distinctive personality, sitting right at the intersection of higher category theory, topology, and geometry… right next to the $n$-Category Café, but there much earlier.

I’ve heard some people say that Charles Ehresmann started out doing great stuff, like defining the notion of ‘connection’, but then switched to weird stuff like differentiable categories, internal categories and $n$-categories. In retrospect this is hilarious… he was just digging deeper into differential geometry than some of the people trying to keep up with him.

Posted at May 27, 2008 1:09 AM UTC

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