Differential Geometry: Cartan's Generalization of Klein's Erlangen Program - Hardcoverby R. W. Sharpe (Author), S. S. Chern (Preface by) Cartan geometries were the first examples of connections on a principal bundle. They seem to be almost unknown these days, in spite of the great beauty and conceptual power they confer on geometry. The aim of the present book is to fill the gap in the literature on differential geometry by the missing notion of Cartan connections. Although the author had in mind a book accessible to graduate students,