简介:LetGbeap-group(poddprime)andletX=Cay(G,S)bea4-valentconnectedCayleygraph.ItisshownthatifGhasnilpotentclass2,thentheautomorphismgroupAut(X)ofXisisomorphictothesemidirectproductGRAut(G,S),whereGRistherightregularrepresentationofGandAut(G,S)isthesubgroupoftheautomorphismgroupAut(G)ofGwhichfixesSsetwise.HowevertheresultisnottrueifGhasnilpotentclass3andthispaperprovidesacounterexample.