A group G admits an n-partite digraphical representation if there exists a regular digraph Γ such that the automorphism Aut(Γ) of satisfies following properties: is isomorphic to G, acts semiregularly on vertices and orbits vertex set form partition into n parts giving structure Γ. In this paper, for every positive integer n, we classify finite groups admitting representation.

We find a relationship between regular embeddings of G, an elementary abelian p-group of order p, into unipotent upper triangular matrices with entries in Fp and commutative dimension n degree 2 polynomial formal groups with nilpotent upper triangular structure matrices. We classify the latter when n = 3 up to linear isomorphism, and use that classification to determine the number of Hopf Galoi...

Suppose V ⊆ W are models of ZFC with the same ordinals, and that for all regular cardinals κ in W , V satisfies κ. If W \ V contains a sequence r : ω → γ for some ordinal γ, then for all cardinals κ < λ in W with κ regular in W and λ ≥ γ, (Pκ(λ)) \ V is stationary in (Pκ(λ)) . That is, a new ω-sequence achieves global co-stationarity of the ground model.

A graph Γ with diameter d is strongly distance-regular if Γ is distanceregular and its distance-d graph Γd is strongly regular. The known examples are all the connected strongly regular graphs (i.e. d = 2), all the antipodal distanceregular graphs, and some distance-regular graphs with diameter d = 3. The main result in this paper is a characterization of these graphs (among regular graphs with...

For any 2-distance set X in the n-dimensional binary Hamming spaceHn, let ΓX be the graph with X as the vertex set and with two vertices adjacent if and only if the distance between them is the smaller of the two nonzero distances in X. The binary spherical representation number of a graph Γ, or bsr Γ , is the least n such that Γ is isomorphic to ΓX , where X is a 2-distance set lying on a sphe...

Let Γ = (X, R) denote a distance-regular graph with diameter D ≥ 3 and distance function δ. A (vertex) subgraph ∆ ⊆ X is said to be weak-geodetically closed whenever for all x, y ∈ ∆ and all z ∈ X, δ(x, z) + δ(z, y) ≤ δ(x, y) + 1 −→ z ∈ ∆. Γ is said to be D-bounded whenever for all x, y ∈ X, x, y are contained in a common regular weak-geodetically closed subgraph of diameter δ(x, y). Assume Γ i...

An important property of strongly regular graphs is that the second subconstituent of any primitive strongly regular graph is always connected. Brouwer asked to what extent this statement can be generalized to distanceregular graphs. In this paper, we show that if γ is any vertex of a distanceregular graph Γ and t is the index where the standard sequence corresponding to the second largest eige...

We consider Cayley graphs Γ over dihedral groups, dihedrants for short, which admit an automorphism group G acting regularly on the arc set of Γ . We prove that, if D2n ≤G≤ Aut(Γ ) is a regular dihedral subgroup of G of order 2n such that any of its index 2 cyclic subgroups is core-free in G, then Γ belongs to the family of graphs of the form (Kn1 ⊗ · · · ⊗Kn )[Kc m], where 2n= n1 · · ·n m, and...

Let G be a finite group, and let 1G 6∈ S ⊆ G. A Cayley di-graph Γ = Cay(G,S) of G relative to S is a di-graph with a vertex set G such that, for x, y ∈ G, the pair (x, y) is an arc if and only if yx−1 ∈ S. Further, if S = S−1 := {s−1|s ∈ S}, then Γ is undirected. Γ is conected if and only if G = 〈s〉. A Cayley (di)graph Γ = Cay(G,S) is called normal if the right regular representation of G is a ...

The aim of this paper is to investigate the ideal theory of Γ-semirings based on intersectional soft sets. Some basic operations are investigated and some related properties are also studied. Finally, some characterizations of regular and intra-regular Γ-semirings are obtained by means of soft intersectional ideals (bi-ideals, quasi-ideals).