In this note, we derive a uniqueness theorem for minimal graphs of general
codimension under certain restrictions closed related to the convexity (not
strict convexity) of the area functional with respect to singular values,
improving the result in \cite{L-O-T}. The crucial step of the proof is to show
the local linearity of the singular value vectors along the geodesic homotopy
of two given minimal maps.Comment: 8 page