Approximative conjunctions processing by multi-valued logic

We study a knowledge base composed of facts and rules of a linguistic nature. We attribute a linguistic degree to each proposition which represents its veracity. A problem encountered is the following: “When the premise part of a production rule is a conjunction of several propositions and when we observe each of these propositions with some degree, what global degree should we attribute to the observation, so that we can infer via the rule? We propose a method in order to express the neighbourhood degree between a rule and an observation evaluated on the same scale or on two different scales