Knowledge Representation using Frames in Artificial Intelligence

Knowledge Representation

Frames are more structured form of packaging knowledge, - used for representing objects, concepts etc.
Frames are organized into hierarchies or network of frames.
Lower level frames can inherit information from upper level frames in network.
Nodes are connected using links viz.,

            → subc (links two class frames, one of which is subclass of other e.g., science_faculty class is ako of faculty class),
            → is_a (connects a particular instance of a class frame e.g., Renuka is_a science_faculty)
            → a_part_of (connects two class frames one of which is contained in other e.g., faculty class is_part_of department class).
           → Property link of semantic net is replaced by SLOT fields.

A frame may have any number of slots needed for describing object. e.g.,

- faculty frame may have name, age, address, qualification etc as slot names.

Each frame includes two basic element : slots and facets.

          - Each slot may contain one or more facets (called fillers) which may take many forms such as :
   ⇒value (value of the slot),
   ⇒default (default value of the slot),
   ⇒range (indicates the range of integer or enumerated values, a slot can have),
⇒demons (procedural attachments such as if_needed, if_deleted, if_added etc.) and
⇒other (may contain rules, other frames, semantic net or any type of other information).

Frame Network - Example

Detailed Representation of Frame Network

Description of Frames

Each frame represent either a class or an instance.
Class frame represents a general concept whereas instance frame represents a specific occurrence of the class instance.
Class frame generally have default values which can be redefined at lower levels.
If class frame has actual value facet then decedent frames can not modify that value.
Value remains unchanged for subclasses and instances.

Inheritance in Frames

Suppose we want to know nationality or phone of an instance-frame13.
These information are not given in this frame.
Search will start from frame13 in upward direction till we get our answer or have reached root frame.
The frame can be easily represented in prolog by choosing predicate name as frame with two arguments.
First argument is the name of the frame and second argument is a list of slot - facet pair.

Features of Frame Representations