Exam P4/5

Question 1

What was the primary motivation behind the development of Frame Systems and KEE?

Answer 1

Find a way to provide a more natural and organized way to represent knowledge by bundling all known information about a particular entity into a single object (a frame or unit), rather than having it scattered across multiple propositions as in logic-based systems.
This object oriented approach aimed to mirror how humans intuitively understand concepts, with associated expectations and characteristics encapsulated together.
KEE, being a tool to build Expert Systems, adopted this Frame System approach as its basis for knowledge representation.

Question 2

There are two main types of slots in KEE: member slots and own slots. Explain the key differences between these two types of slots and how they behave with respect to inheritance in a KEE knowledge base

Answer 2

Member slots
- Represent attributes or properties that are common to all members of a class
- Are propagated down the class hierarchy to all subclasses and instances
- When a member slot is inherited by an instance, it is transformed into n own slot of that instance

Own slots
- Represent attributes that are specific to the unit (class or instance) where the slot is directly attached
- Are not propagated down the class hierarchy
- Instances can only have own slots
- Own slots attached to classes represent a property of the class itself

Question 3

What are facets in the context of KEE slots?

Answer 3

Facets represent properties of attributes. They characterize particular aspects of slots, essentially acting as attributes of attributes.

Question 4

We have talked about daemons as a component of Frame Systems. Describe what daemons are and how they function in KEE. Describe their operation and what kind of reasoning they exemplify

Answer 4

Daemons are pieces of code that are procedurally attached to slots within frames.
When the value of a slot to which a daemon is attached is changed, that daemon is automatically triggered or “fired”. This execution can then lead to changes in the values of other slots within the knowledge base.
Daemons exemplify forward processing. A change triggers a predefined action propagating the effects of changes automatically

Question 5

Describe the structure of a KEE knowledge base? What are the fundamental building blocks, and how are they organized? Explain the concept of multiple inheritance in this context

Answer 5

A KEE knowledge base is structured as one or more hierarchies of frames called units.
- Units represent classes or instances and are described by attribute-value pairs using slots
- Slots represent attributes of units
- Facets define properties of slots, such as value type, cardinality, etc

Question 6

There is three types of reasoning supported by Frame Systems and KEE. List and briefly explain each of these types of reasoning

Answer 6

Inheritance of attributes
Attributes off a slot or class are generally automatically propagated down the hierarchy to its subclasses and instances.

Procedural attachment
Attaching procedures to slots within frames, also known as servants or daemons. Are automatically executed when a value is accessed or changed, enabling dynamic behavior and the integration of procedural knowledge.

Rule-based systems
These systems also employ if-then rules. KEE supports both forward and backward reasoning. These rules can formalize empirical knowledge from domain experts.