On conditional coloring of some graphs

For integers r and k > 0(k>r),a conditional (k, r)-coloring of a graph G is a proper k-coloring of G such that every vertex v of G has at least min{r,d(v)} differently colored neighbors, where d(v) is the degree of v. In this note, for different values of r we obtain the conditional chromatic number of a grid $G(2,n) \cong P_2 \ \Box \ P_n$, $C_n^2$ and the strong product of $P_n$ and $P_m$ (n,m being positive integers). Also, for integers $n \geq 3$ and $t \geq 1$ the second order conditional chromatic number (also known as dynamic chromatic number) of the (t,n)-web graph is obtained.Comment: 9 pages: accepted for the 76th annual conference of the Indian Mathematical Society,27-30 December 2010,Surat,Indi

Conditional and Unique Coloring of Graphs

For integers $k, r > 0$, a conditional $(k,r)$-coloring of a graph $G$ is a proper $k$-coloring of the vertices of $G$ such that every vertex $v$ of degree $d(v)$ in $G$ is adjacent to at least $\min\{r, d(v)\}$ differently colored vertices. Given $r$, the smallest integer $k$ for which $G$ has a conditional $(k,r)$-coloring is called the $r$th order conditional chromatic number $\chi_r(G)$ of $G$. We give results (exact values or bounds for $\chi_r(G)$, depending on $r$) related to the conditional coloring of some graphs. We introduce \emph{unique conditional colorability} and give some related results. (Keywords. cartesian product of graphs; conditional chromatic number; gear graph; join of graphs.)Comment: Under review in International Journal of Computer Mathematic