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Artificial Intelligence
Lecture 4 Artificial Intelligence Sanaullah Manzoor CS&IT, Lahore Leads University 1
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Knowledge Representation
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Overview Knowledge Processing
Motivation Objectives Knowledge Types Knowledge Representation Method Semantic Networks Frames Production Rules 3
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Knowledge Representation Methodologies
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Before we begin the methods.. Let’s see this
There is a common method used for many non-AI (databases) representation, namely Object-Attribute-Value (O-A-V) Triplets An O-A-V is a more complex type of proposition (fact). It divides statement into three (3) parts as shown: price shirt RM39 attribute value object
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There can be single or multiple attribute facts
blue color shirt size XL cost rm39 There can also be single or multiple value facts .
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Semantic Networks A semantic net has a binary relation
Concepts are represented by nodes Links between nodes represent the relationships Drawbacks: Disjunctive and conjunctive information cannot be included into semantic nets E.g. apple can be either green or red E.g. panda has color black and white
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Semantic Networks (II)
Examples of relationship labeled on arcs (notice that there is an underscore) is_a has_a has_part Examples of concepts (nodes) bird person book famous intelligent
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A semantic net that represents a bird’s property
has_covering has_property bird feathers flies is_a size has_color small blue bluebird
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Draw a semantic network for the following description:
Exercise: Draw a semantic network for the following description: Lab is a room. Lab has a door. Lab has computers. Printer is in lab. Laser printer is a Printer.
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Inheritance in Semantics Nets
Breathe Animal Move can can Fly Bird Wings Feathers can has has Penguin We shall see this later can Canary Sing Yellow Animal’s properties are inherited to Bird and Bird’s properties are inherited to a bird species called canary is
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Frames The idea behind frames is to store information in meaningful chunks. This frame has 4 slots: BOOK Title : Qualitative Reasoning Author : Ken D. Forbus Publisher : Prentice-Hall Year : 2000
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Frame Description Hotel Room specialisation of: room
location: the hotel contains: bed, chair & phone Hotel Phone specialisation of: phone use: calling room service billing: through room Hotel Bed superclass: bed size: king contains: mattress, pillow, etc. ::
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Frames You should be able to see now :
that a frame describes an object by embedding all the information about that object in “slots” that slots are commonly known in programming terms as fields or attributes with associated value this is an advantage (discuss in later part) that a frame is similar to a database record that a frame describes typical instances of the concepts they represent
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Converting from Frames to Semantics Nets
has_a book has_a date publisher is_a is_a has_a author novel encyclopedia is_a Forbus editor has_a
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Converting from Frames to Semantics Nets
date author Forbus book publisher editor has_a is_a
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