This is my personal rendition of the classic Action Conversation diagram.
See Arrows diagram
OfMakesClarifytoMakestoRequiresUnderstandsToInitiated byMakesTakes Care of PromiseAgrees tofromMakesChoosesChoosesChoosesChoosesChoosesMakestoActionConversationCustomerT1PerformerT1PromiseDeclareCompleteRequestCoStsCustomerT3DeclareSatisfiedPerformerT3CompleteCustomerT2PerformerT2AcceptCounterOfferDeclineWithdrawWithdrawRenegeWithdrawDeclareDissatisfied