英语翻译
According to the principle of relevance,whenever a person sets out to communicate something,he automatically communicates the presumption that what he is going to say is believed to be optimally relevant to us.Thus it can be seen that the goal of human communication is optimal relevance,that is,an expectation on the part of the audience that his attempt at interpretation will yield adequate contextual effect at minimal processing cost.To put it more clearly,an utterance,on a given interpretation is optimally relevant if and only if：(a) it achieves contextual effects to be worth the addressee's attention; (b) it puts the addressee to no unjustifiable expenditures of processing effort in achieving those effects.