Classification of normal operators in spaces with indefinite scalar product of rank 2 Original Research Article

A finite-dimensional complex space with indefinite scalar product [.,.] having v− = 2 negative squares and v+ ≥ 2 positive ones is considered. The paper presents a classification of operators that are normal with respect to this product. It relates to the study by Gohberg and Reichstein in which the similar classification was obtained for the case v = min{v−, v+} = 1.