In this paper we prove that every 2-local derivation from any symmetric digraph algebra into itself is a derivation . Moreover we give an example to show that the conclusion may not be true if it has not the condition of symmetry .

本文证明了 对称 digraph代数上的每一个2-局部导子都是导子，并给出一个例子说明该结论在非对称digraph代数上不成立。

The exponent set of symmetric digraph with odd girth R

奇围长为r的 对称 图的指数集

Furthermore we also describe a characterization of the symmetric digraph with odd girth r whose exponent is equal to 2n-r-1 .

并刻划了指数为2n-r-1的奇围长为r的 对称 图的特征。