This paper reports a case study of a logical inference model of emotion applied to ‘chagrin.’
Chagrin caused by a failure in executing a plan is examined from a problem solving view point. When a state of chagrin arises, people try to be released from it by means of behavior patterns such as those depicted in Aesop's fable of sour grapes. In additon, a logical dependency relation among knowledge units employed in this process is described.