O. Kassabov

activity

20072026

most citedOn the axiom of planes and the axiom of spheres in the almost Hermitian geometry

7 citations · 30 across the 40 of their papers we have counts for

collaborators

41 papers

math.DG2026

Basic invariants for time-like surfaces in $R_{1}^{3}$ with real asymptotic lines

Ognian Kassabov

The geometrically defined wide class of time-like surfaces in $R^{3}$ , admitting real asymptotic lines is considered. A fundamental theorem of Bonnet-type is obtained for the…

math.DG2025

Canonical parameters on a surface in $R^{4}$

Ognian Kassabov, Velichka Milousheva

In the present paper, we study surfaces in the four-dimensional Euclidean space $R^{4}$ . We define special principal parameters, which we call canonical, on each surface wit…

math.DG2024

Relation between the minimal Lorentz surfaces in $R_{2}^{4}$ and $R_{1}^{3}$

Krasimir Kanchev, Ognian Kassabov, Velichka Milousheva

In this paper we give Weierstrass-type representation formulas for the null curves and for the minimal Lorentz surfaces in the Minkowski 3-space $R_{1}^{3}$ using real-valued f…

math.DG2023

Minimal Timelike Surfaces in the Lorentz-Minkowski 3-space and Their Canonical Parameters

Ognian Kassabov, Velichka Milousheva

We study minimal timelike surfaces in $R_{1}^{3}$ using a special Weierstrass-type formula in terms of holomorphic functions defined in the algebra of the double (split-complex…

math.DG2021

Canonical Coordinates and Natural Equation for Lorentz Surfaces in $R_{1}^{3}$

Krasimir Kanchev, Ognian Kassabov, Velichka Milousheva

We consider Lorentz surfaces in $R_{1}^{3}$ satisfying the condition $H^{2} - K \neq = 0$ , where $K$ and $H$ are the Gauss curvature and the mean curvature, respectively, and call the…

math.DG2021

Explicit Solving of the System of Natural PDEs of Minimal Lorentz Surfaces in $R_{2}^{4}$

Krasimir Kanchev, Ognian Kassabov, Velichka Milousheva

A minimal Lorentz surface in $R_{2}^{4}$ is said to be of general type if its corresponding null curves are non-degenerate. These surfaces admit canonical isothermal and canoni…

Basic invariants for time-like surfaces in R13​ with real asymptotic lines

Canonical parameters on a surface in R4

Relation between the minimal Lorentz surfaces in R24​ and R13​

Minimal Timelike Surfaces in the Lorentz-Minkowski 3-space and Their Canonical Parameters

Canonical Coordinates and Natural Equation for Lorentz Surfaces in R13​

Explicit Solving of the System of Natural PDEs of Minimal Lorentz Surfaces in R24​

Basic invariants for time-like surfaces in $R_{1}^{3}$ with real asymptotic lines

Canonical parameters on a surface in $R^{4}$

Relation between the minimal Lorentz surfaces in $R_{2}^{4}$ and $R_{1}^{3}$

Canonical Coordinates and Natural Equation for Lorentz Surfaces in $R_{1}^{3}$

Explicit Solving of the System of Natural PDEs of Minimal Lorentz Surfaces in $R_{2}^{4}$