The prime graph of a finite group $G$ is denoted by $Gamma(G)$ whose vertex set is $pi(G)$ and two distinct primes $p$ and $q$ are adjacent in $Gamma(G)$, whenever $G$ contains an element with order $pq$. We say that $G$ is unrecognizable by prime graph if there is a finite group $H$ with $Gamma(H)=Gamma(G)$, in while $Hnotcong G$. In this paper, we consider finite groups with the same prime gr...

let g be a (p, q) graph. let f : v (g) → {1, 2, . . . , k} be a map. for each edge uv, assign the label gcd (f(u), f(v)). f is called k-prime cordial labeling of g if |vf (i) − vf (j)| ≤ 1, i, j ∈ {1, 2, . . . , k} and |ef (0) − ef (1)| ≤ 1 where vf (x) denotes the number of vertices labeled with x, ef (1) and ef (0) respectively denote the number of edges labeled with 1 and not labeled with 1....

The prime graph of a finite group $G$ is denoted by$ga(G)$. A nonabelian simple group $G$ is called quasirecognizable by primegraph, if for every finite group $H$, where $ga(H)=ga(G)$, thereexists a nonabelian composition factor of $H$ which is isomorphic to$G$. Until now, it is proved that some finite linear simple groups arequasirecognizable by prime graph, for instance, the linear groups $L_...

By Ulam’s conjecture every finite graph G can be reconstructed from its deck of vertex deleted subgraphs. The conjecture is still open, but many special cases have been settled. In particular, one can reconstruct Cartesian products. We consider the case of k-vertex deleted subgraphs of Cartesian products, and prove that one can decide whether a graph H is a kvertex deleted subgraph of a Cartesi...

It is shown that every connected vertex-transitive graph of order 4p, where p is a prime, is hamiltonian with the exception of the Coxeter graph which is known to possess a Hamilton path. In 1969, Lovász [22] asked if every finite, connected vertex-transitive graph has a Hamilton path, that is, a path going through all vertices of the graph. With the exception of K 2 , only four connected verte...

let $g$ be a finite group and $gamma(g)$ the prime graph of $g$‎. ‎recently people have been using prime graphs to study simple groups‎. ‎naturally we pose a question‎: ‎can we use prime graphs to study almost‎ ‎simple groups or non-simple groups? in this paper some results in‎ ‎this respect are obtained and as follows‎: ‎$gcong s_p$ if and only‎ ‎if $|g|=|s_p|$ and $gamma(g)=gamma(s_p)$‎, ‎whe...

In this paper, we study oriented bipartite graphs. particular, introduce “bitransitive” Several characterizations of bitransitive bitournaments are obtained. We show that bitounaments equivalent to acyclic bitournaments. As applications, characterize with Hamiltonian paths, determine the number non-isomorphic a given order, and solve graph-isomorphism problem in linear time for Next, prove well...

Let pn denote the nth prime. The prime number graph is the set of lattice points (n, pn), n = 1, 2.We show that for every k there are k such points that are collinear. By considering the convex hull of the prime number graph, we show that there are infinitely many n such that 2pn < pn_¡ + Pn+Ifor all positive i < n. By a similar argument, we show that there are infinitely many n for which pn > ...

Let G be a (p, q) graph. Let f : V (G) → {1, 2, . . . , k} be a map. For each edge uv, assign the label gcd (f(u), f(v)). f is called k-prime cordial labeling of G if |vf (i) − vf (j)| ≤ 1, i, j ∈ {1, 2, . . . , k} and |ef (0) − ef (1)| ≤ 1 where vf (x) denotes the number of vertices labeled with x, ef (1) and ef (0) respectively denote the number of edges labeled with 1 and not labeled with 1....

Felice Russo _\/tcr()J7 7ecil17()/o!!:1' 110/\' '.-1 re~~CIl7() (-1(1) IW(1' In this note v.e report the results regarding ,he check of the third Smarandache conjecture on primes [1 J.[2] for P ~ 2 and 2 ~ k ~ 10, In the range analysed the conjecture is true, n \loreover. according to experimental data obtained. it seems likely that the conjecture is true for all primes and for all positi\'e va...