An odd graceful labeling of a graph ( , ) G V E = is a function : ( ) {0,1,2, . . .2 ( ) 1} f V G E G → − such that | ( ) ( )| f u f v − is odd value less than or equal to 2 ( ) 1 E G − for any , ( ) u v V G ∈ . In spite of the large number of papers published on the subject of graph labeling, there are few algorithms to be used by researchers to gracefully label graphs. This work provides gene...

Let G be a simple graph with no even cycle, called an odd-cycle graph. Cavers et al. [Linear Algebra Appl. 436(12):4512-1829, 2012] showed that the spectral radius of G is the same for every orientation σ of G, and equals the maximum matching root of G. They proposed a conjecture that the graphs which attain the maximum skew spectral radius among the odd-cycle graphs G of order n are isomorphic...

A graph G is an odd-circuit tree if every block of G is an odd length circuit. It is proved in this paper that the product of every pair of graphs G and H admits a nowhere-zero 3-flow unless G is an odd-circuit tree and H has a bridge. This theorem is a partial result to the Tutte’s 3-flow conjecture and generalizes a result by Imrich and Skrekovski [7] that the product of two bipartite graphs ...

We present a necessary and sufficient condition for a graph of odd-girth 2k + 1 to bound the class of K4-minor-free graphs of odd-girth (at least) 2k + 1, that is, to admit a homomorphism from any such K4-minor-free graph. This yields a polynomial-time algorithm to recognize such bounds. Using this condition, we first prove that every K4-minor free graph of odd-girth 2k+1 admits a homomorphism ...

The main result of the papzer is that any planar graph with odd girth at least 10k À 7 has a homomorphism to the Kneser graph G 2k‡1 k , i.e. each vertex can be colored with k colors from the set f1; 2;. .. ; 2k ‡ 1g so that adjacent vertices have no colors in common. Thus, for example, if the odd girth of a planar graph is at least 13, then the graph has a homomorphism to G 5 2 , also known as...

We introduce weak oddness ωw, a new measure of uncolourability of cubic graphs, defined as the least number of odd components in an even factor. For every bridgeless cubic graph G, %(G) ≤ ωw(G) ≤ ω(G), where %(G) denotes the resistance of G and ω(G) denotes the oddness of G, so this new measure is an approximation of both oddness and resistance. We demonstrate that there are graphs G satisfying...

Graph coloring is a general solution to the scheduling problem. Variants of the scheduling problem abound in computer engineering CAD problems. BDDs, which have efficient set and data compression properties, are a tool useful for solving NP-Complete problems such as the graph coloring problem. This report explores BDD techniques helpful for determining the chromatic number of a graph, enumerati...

We present a novel approach to solve quantified boolean formulas with one quantifier alternation (2QBF). The algorithm incrementally adds new constraints to the formula until the constraints describe a unique Skolem function or until the absence of a Skolem function is detected. Backtracking is required if the absence of Skolem functions depends on the newly introduced constraints. We present t...

Let G be a graph with its vertices and edges. On defining bijective function ρ:V(G) →{0,1,...,p}. For each edge assign the label 1 if ρ*(ab)= | ρ(a) 2 −ρ(b) /ρ(a)−ρ(b) is odd or 0 otherwise such that |eρ(1) − eρ(0)| ≤ then labeling called as divided square difference cordial graph. We prove in this paper for relatively possible set of spider graphs atmost one legs greater than namely J(SP(1 m ,...