A Combinatorial Theorem on Systems of Sets

عدد تناوبی گراف‌ها

In 2015, Alishahi and Hajiabolhassan introduced the altermatic number of graphs as a lower bound for the chromatic number of them. Their proof is based on the Tucker lemma, a combinatorial counterpart of the Borsuk-Ulam theorem, which is a well-known result in topological combinatorics. In this paper, we present a combinatorial proof for the Alishahi-Hajiabolhassan theorem. 

ON COMPACTNESS AND G-COMPLETENESS IN FUZZY METRIC SPACES

In [Fuzzy Sets and Systems 27 (1988) 385-389], M. Grabiec in- troduced a notion of completeness for fuzzy metric spaces (in the sense of Kramosil and Michalek) that successfully used to obtain a fuzzy version of Ba- nachs contraction principle. According to the classical case, one can expect that a compact fuzzy metric space be complete in Grabiecs sense. We show here that this is not the case,...

A convex combinatorial property of compact sets in the plane and its roots in lattice theory

K. Adaricheva and M. Bolat have recently proved that if $,mathcal U_0$ and $,mathcal U_1$ are circles in a triangle with vertices $A_0,A_1,A_2$, then there exist $jin {0,1,2}$ and $kin{0,1}$ such that $,mathcal U_{1-k}$ is included in the convex hull of $,mathcal U_kcup({A_0,A_1, A_2}setminus{A_j})$. One could say disks instead of circles.Here we prove the existence of such a $j$ and $k$ ...

A Remark on a Remark by Macaulay or Enhancing Lazard Structural Theorem

On fixed point theorems in fuzzy metric spaces using a control function

In this paper, we generalize Fuzzy Banach contraction theorem establishedby V. Gregori and A. Sapena [Fuzzy Sets and Systems 125 (2002) 245-252]using notion of altering distance which was initiated by Khan et al. [Bull. Austral.Math. Soc., 30(1984), 1-9] in metric spaces.

?-Independent and Dissociate Sets on Compact Commutative Strong Hypergroups

In this paper we define ?-independent (a weak-version of independence), Kronecker and dissociate sets on hypergroups and study their properties and relationships among them and some other thin sets such as independent and Sidon sets. These sets have the lacunarity or thinness property and are very useful indeed. For example Varopoulos used the Kronecker sets to prove the Malliavin theorem. In t...