Though the transitive closure of a reflexive and symmetric fuzzy relation R is unique and there are several algorithms to calculate it, there can be many transitive openings (maximal T -indistinguishability operators among the ones smaller than or equal to R). This paper presents a method to calculate transitive openings of a reflexive and symmetric fuzzy relation R. It is worth noticing that a...

The transitive closure of a reflexive, symmetric, analytic relation is an analytic equivalence relation. Does some smaller class contain the transitive closure of every reflexive, symmetric, closed relation? An essentially negative answer is provided here. Every analytic equivalence relation on an arbitrary Polish space is Borel embeddable in the transitive closure of the union of two smooth Bo...

A method to compute the transitive closure, a transitive opening and a transitive approximation of a reflexive and symmetric fuzzy relation is given. Other previous methods in literature compute just the transitive closure, some transitive approximations or some transitive openings. The proposed algorithm computes the three different similarities that approximate a proximity for the computation...

A subgroup G of automorphisms of a graph X is said to be 1 2-transitive if it is vertex and edge but not arc-transitive. The graph X is said to be 1 2-transitive if Aut X is 1 2-transitive. The graph X is called one-regular if Aut X acts regularly on the set arcs of X. The interplay of three diierent concepts of maps, one-regular graphs and 1 2-transitive group actions on graphs of valency 4 is...

Transitive closures of binary relations and relations α with the property that any two α-sequences connecting two given elements are of the same length are investigated. Vyšetřuj́ı se tranzitivńı uzávěry binárńıch relaćı a relaćı α s vlastnost́ı, že každé dvě α-posloupnosti spojuj́ıćı dané dva prvky maj́ı stejnou délku. The present short note collects a few elementary observations concerning the tr...

A regular covering projection ℘: X̃ → X of connected graphs is G-admissible if G lifts along ℘. Denote by G̃ the lifted group, and let CT(℘) be the group of covering transformations. The projection is called G-split whenever the extension CT(℘) → G̃ → G splits. In this paper, split 2-covers are considered, with a particular emphasis given to cubic symmetric graphs. Supposing that G is transitive o...

Transitive tournament (including transitive triangle) and its blow-up have some symmetric properties. In this work, we establish an analogue result of the Erdös-Stone theorem weighted digraphs with a forbidden tournament. We give stability oriented graphs triangles show that almost all are bipartite, which reconfirms strengthens conjecture Cherlin.

We show that an action of SL(2, p), p ≥ 7 an odd prime such that 4 6 | (p − 1), has exactly two orbital digraphs Γ1, Γ2, such that Aut(Γi) admits a complete block system B of p + 1 blocks of size 2, i = 1, 2, with the following properties: the action of Aut(Γi) on the blocks of B is nonsolvable, doubly-transitive, but not a symmetric group, and the subgroup of Aut(Γi) that fixes each block of B...