let $g=(v, e)$ be a graph. by emph{directional labeling (ord-labeling)} of an edge $x=uv$ of $g$ by an ordered $n$-tuple$(a_1,a_2,...,a_n)$, we mean a labeling of the edge $x$ such thatwe consider the label on $uv$ as $(a_1,a_2,...,a_n)$ in thedirection from $u$ to $v$, and the label on $x$ as$(a_{n},a_{n-1},...,a_1)$ in the direction from $v$ to $u$. inthis paper, we study graphs, called emph{...

With any G-symmetric graph admitting a nontrivial G-invariant partition B, we may associate a natural ‘‘cross-sectional’’ geometry, namely the 1-design DðBÞ 1⁄4 ðB; BðBÞ; IÞ in which IC for 2B and C 2 BðBÞ if and only if is adjacent to at least one vertex in C, where B2B and BðBÞ is the neighbourhood of B in the quotient graph B of with respect to B. In a vast number of cases, the dual 1-design...