We generalize the celebrated results of Bernhard Riemann and Gaston Darboux: we give necessary and sufficient conditions for a bilinear form to be flat. More precisely, we give explicit necessary and sufficient conditions for a tensor field of type (0, 2) which is not necessary symmetric or skew-symmetric, and is possibly degenerate, to have constant entries in a local coordinate system.
Details
Title
Bernhard Riemann 1861 revisited: existence of flat coordinates for an arbitrary bilinear form
Grant
The research of S. Bandyopadhyay is supported by the MATRICS research project grant (File No. MTR/2017/000414): MTR/2017/000414 MATRICS research project grant: MA 2565/6 Swiss SNF DFG: DP210100951 ARC Discovery Programme