All a b c d e f g h i j k l m n o p q r s t u v w x y z Other

Previous Page 67 Next

Displaying 1321 – 1340 of 2516

Showing per page

On generalizations of fuzzy metric spaces

Yi Shi, Wei Yao (2023)

Kybernetika

The aim of the paper is to present three-variable generalizations of fuzzy metric spaces in sense of George and Veeramani from functional and topological points of view, respectively. From the viewpoint of functional generalization, we introduce a notion of generalized fuzzy 2-metric spaces, study their topological properties, and point out that it is also a common generalization of both tripled fuzzy metric spaces proposed by Tian et al. and ℳ -fuzzy metric spaces proposed by Sedghi and Shobe. Since...

On geodesics of phyllotaxis

Roland Bacher (2014)

Confluentes Mathematici

Seeds of sunflowers are often modelled by n ⟼ ϕ θ ( n ) = n e 2 i π n θ leading to a roughly uniform repartition with seeds indexed by consecutive integers at angular distance 2 π θ for θ the golden ratio. We associate to such a map ϕ θ a geodesic path γ θ : ℝ > 0 ⟶ PSL 2 ( ℤ ) ∖ ℍ of the modular curve and use it for local descriptions of the image ϕ θ ( ℕ ) of the phyllotactic map ϕ θ .

On Gnomons

Jan M. Aarts, Robbert. J. Fokkink (2003)

Matematički Vesnik

On Hadwiger's problem on inner parallel bodies

Eugenia Saorín (2009)

Banach Center Publications

We consider the problem of classifying the convex bodies in the 3-dimensional space depending on the differentiability of their associated quermassintegrals with respect to the one-parameter-depending family given by the inner/outer parallel bodies. It turns out that this problem is closely related to some behavior of the roots of the 3-dimensional Steiner polynomial.

On hyperbolic virtual polytopes and hyperbolic fans

Gaiane Panina (2006)

Open Mathematics

Hyperbolic virtual polytopes arose originally as polytopal versions of counterexamples to the following A.D.Alexandrov’s uniqueness conjecture: Let K ⊂ ℝ3 be a smooth convex body. If for a constant C, at every point of ∂K, we have R 1 ≤ C ≤ R 2 then K is a ball. (R 1 and R 2 stand for the principal curvature radii of ∂K.) This paper gives a new (in comparison with the previous construction by Y.Martinez-Maure and by G.Panina) series of counterexamples to the conjecture. In particular, a hyperbolic...

On hyperplanes and semispaces in max–min convex geometry

Viorel Nitica, Sergeĭ Sergeev (2010)

Kybernetika

The concept of separation by hyperplanes and halfspaces is fundamental for convex geometry and its tropical (max-plus) analogue. However, analogous separation results in max-min convex geometry are based on semispaces. This paper answers the question which semispaces are hyperplanes and when it is possible to “classically” separate by hyperplanes in max-min convex geometry.

On light subgraphs in plane graphs of minimum degree five

Stanislav Jendrol', Tomáš Madaras (1996)

Discussiones Mathematicae Graph Theory

A subgraph of a plane graph is light if the sum of the degrees of the vertices of the subgraph in the graph is small. It is well known that a plane graph of minimum degree five contains light edges and light triangles. In this paper we show that every plane graph of minimum degree five contains also light stars K 1 , 3 and K 1 , 4 and a light 4-path P₄. The results obtained for K 1 , 3 and P₄ are best possible.

Currently displaying 1321 – 1340 of 2516