Doupovec, Miroslav et M. Mikulski, Wlodzimierz, Reduction theorems for principal and classical connections, Acta mathematica Sinica. English series (Print) , 26(1), 2010, pp. 169-184
We prove general reduction theorems for gauge natural operators transforming principal connections and classical linear connections on the base manifold into sections of an arbitrary gauge natural bundle. Then we apply our results to the principal prolongation of connections. Finally we describe all such gauge natural operators for some special cases of a Lie group G.