Ans. Knowledge Representation Schemes

• First Order Predicate Logic: It is the most important representation scheme because it has well developed theory, has reasonable expressive power, and uses valid forms of inferring. A typical statement in this logic might express the family relationship of fatherhood as FATHER(john, jim) where the predicate father is used to express the fact that John is the father of Jim. The greatest weakness of this logic is its limitation as a model for commonsense reasoning.
• Frames: Frames are flexible structures that permit the grouping of closely related knowledge. For example, an object such as a ball and its properties (color, size, function) and its relationship to other objects (to the left of, on top of, and so on) are grouped together into a single structure for easy access.
  Associative Networks: The networks allow easy access to groups of related items. They associate objects with their attributes, and linkages show their relationship to other objects.
• Fuzzy Logic: It is a form of logic used in some expert systems and other artificial-intelligence applications in which variables can have degrees of truthfulness or falsehood represented by a range of values between 1 (true) and 0 (false). With fuzzy logic, the outcome of an operation can be expressed as a probability rather than as a certainty. For example, in addition to being either true or false, an outcome might have such meanings as probably true, possibly true, possibly false, and probably false.
• Modal Logic: It is an extension of classical logic. It was developed to better represent commonsense reasoning by permitting conditions such as likely or possible.
• Object Oriented Representations: It packages an object together with its attributes and functions, therefore, hiding these facts. Operations are performed by sending messages between the objects.