文摘
Consider the differential field K=Q‾(x) with derivation d/dxd/dx. Let some unknowns (components of the unknown vector y=(y1,…,yn)Ty=(y1,…,yn)T) of a linear homogeneous differential system S over K be selected. Denote this set of selected unknowns by s . An unselected unknown yjyj of the system S is called satellite for s if the minimal subfield of a Picard–Vessiot extension over K for S, that contains all selected components of all solutions to S , also contains yjyj component of any solution. We present an algorithm for constructing the set of satellite unknowns for a given linear homogeneous differential system with selected unknowns.