Nonsingularity and symmetry for linear normal maps
Normal maps are single-valued functions expressing conditions for the solution of variational problems. The author discusses the question of the non-singularity of normal maps arising from linear transformations. A related reference by the same author is Math. Oper. Res. 17, No. 3, 691- 714 (1992; Zbl 0777.90063).
scientific article; zbMATH DE number 558703