nLab Charles Ehresmann

Charles Ehresmann was a pioneer in investigating groupoids and then categories for their applications in geometric problems. It is notable that he was a student of Elie Cartan, famous for his work in Analysis. As a consequence, Ehresmann was fascinated by local-to-global problems, which are among the key problems in mathematics and science. This is one reason for his approach to category theory being different from that in the USA, where category theory was founded.

He had a succession of influential students, and among the concepts which he initiated are: fibre bundles, foliations, germs, gerbes, double categories, topological groupoids, Lie groupoids, holonomy, structured categories, …

The journal he founded and edited, Cahiers de Topologie et Géométrie Différentielle Catégoriques, has been continued by his widow, Andree Ehresmann.


Selected writings

Introducing the notion of topological groupoids and Lie groupoids:

  • Charles Ehresmann, Catégories topologiques et categories différentiables, Colloque de Géométrie différentielle globale, Bruxelles, C.B.R.M., (1959) pp. 137-150 (pdf, zbMath:0205.28202)

Introducing the notion of internal categories (or at least something in this direction):

On internalization of mathematical structures via sketches:

category: people

Last revised on March 24, 2021 at 12:58:52. See the history of this page for a list of all contributions to it.