In this note we investigate the structure of contact Lie algebras when the ground field is of characteristic 2. In order to describe the simple constituent of contact Lie algebras, by using computer algebra system, GAP, ...

The (proper) power graph of a group is a graph whose vertex set is the set of all (nontrivial) elements of the group and two distinct vertices are adjacent if one is a power of the other. Various kinds of planarity of ...

Given a pair (X,σ) consisting of a finite tree X and its vertex self-map σ one can construct the corresponding Markov graph Γ(X,σ) which is a digraph that encodes σ-covering relation between edges in X. M-graphs are Markov ...

Let G be a graph with the eigenvalues λ₁(G)≥⋯≥λn(G). The largest eigenvalue of G, λ₁(G), is called the spectral radius of G. Let β(G)=Δ(G)−λ₁(G), where Δ(G) is the maximum degree of vertices of G. It is known that if G is ...

Let Zn be the finite commutative ring of residue classes modulo n with identity and Γ(Zn) be its zero-divisor graph. In this paper, we investigated some properties of nilradical graph, denoted by N(Zn) and non-nilradical ...

For a commutative ring R and an ideal I of R, the ideal-based zero-divisor graph is the undirected graph ΓI(R) with vertices {x∈R−I:xy∈I for some y∈R−I}, where distinct vertices x and y are adjacent if and only if xy∈I. ...

Let S be a pomonoid. In this paper, Pos-S, the category of S-posets and S-poset maps, is considered. One of the main aims of this paper is to draw attention to the notion of weak factorization systems in Pos-S. We show ...