5 papers
On three-dimensional -regular Nijenhuis operators
Dinmukhammed Akpan, Matteo Manenti
The paper discusses the classification of three-dimensional gl-regular Nijenhuis operators and their normal forms. We also prove A.~Bolsinov's conjecture.
Beltrami problem in dimension two: local normal forms
Dinmukhammed Akpan, Alexey Bolsinov
Two (pseudo-)Riemannian metrics are said to be geodesically equivalent if they share the same geodesics considered as unparametrized curves. In 1865, E. Beltrami posed the problem…
Elementary Differential Singularities of Three-Dimensional Nijenhuis Operators
Dinmukhammed Akpan, Andrei Oshemkov
In the paper, three-dimensional Nijenhuis operators are studied that have differential singularities, i.e., such points at which the coefficients of the characteristic polynomials…
Almost Differentially Nondegenerate Nijenhuis Operators
Dinmukhammed Akpan
The paper is devoted to the study of Nijenhuis operators of arbitrary dimension in a neighborhood of a point at which the first coefficients of the characteristic polynom…
Singularities of two-dimensional Nijenhuis operators
Dinmukhammed Akpan
A Nijenhuis operator is a -tensor field on a smooth manifold with vanishing Nijenhuis torsion . At each point , the algebraic type of $L(x…