We outline some of the tools C. Ehresmann introduced in Differential Geometry (fiber bundles, connections, jets, groupoids, pseudogroups). We emphasize two aspects of C. Ehresmann's works: use of Cartan notations for the theory of connections and semi-holonomic jets.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-bc76-0-2, author = {Paulette Libermann}, title = {Charles Ehresmann's concepts in differential geometry}, journal = {Banach Center Publications}, volume = {75}, year = {2007}, pages = {35-50}, zbl = {1116.53001}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-bc76-0-2} }
Paulette Libermann. Charles Ehresmann's concepts in differential geometry. Banach Center Publications, Tome 75 (2007) pp. 35-50. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-bc76-0-2/