Represent the following sentences in first-order logic, using a consistent vocabulary

a) Not all students take both History and Biology.

b) Only one student failed History.

c) Only one student failed both history and biology.

d) The best score in History was better than the best score in Biology.

e) Every person who dislikes all vegetarians is smart.

f) No person likes a smart vegetarian.

g) There is a woman who likes all men who are not vegetarians.

h) There is a barber who shaves all men in town who do not shave themselves.

i) No person likes a professor unless the professor is smart.

j) Politicians can fool some of the people all of the time, and they can fool all of the people some of the time , but they can’t fool all of the people all of the time.

BUILDING A KNOWLEDGE BAGEAfter learning this lesson we can develop a methodology for building

knowledge bases for particular domains

The previous lessons we showed that first order logic is a powerful tool for knowledge representation and reasoning. However , a logic by itself consists of only the syntax, semantics, and proof theory. A logic does not offer any guidance as to what facts should be expressed , nor what vocabulary should be used to express them

The process of building a knowledge base is called Knowledge engineering

The knowledge engineering will usually interview the real experts to become educated about the domain and to elicit the required knowledge ,

in a process called knowledge acquisition

Knowledge Engineering VS. Programming

A useful analogy can be made between knowledge engineering and programming. Both activities can be seen as consisting of for steps:

Knowledge Engineering Programming

1) Choosing a logic

2) Building a Knowledge base

3) Implementing the proof theory.

4) Inferring new facts.

1) Choosing a programming language.

2) Writing a program.

3) Choosing or writing a compiler

4) Running a program

Knowledge EngineeringThe knowledge engineer must understand enough about the domain in question to represent the important objects and relationships. He or she must also understand enough about the representation language to correctly encode these facts. Moreover, the knowledge engineer must also understand enough about the implementation of the inference procedure to assure that queries can be answered in a reasonable amount of time. To help focus the development of a knowledge base and to integrate the engineer's thinking at the three levels, the

following five-step methodology can be used:

Decide what to talk aboutDecide on a vocabulary of predicates

Encode general knowledge about the domain

Encode a description of the specific problem instancePose queries to the inference procedure and get answer

THE ELECTRONIC CIRCUITS DOMAIN

Encode general rulesOne sign that we have a good ontology is that there are very few general rules that need to be specified. A sign that we have a good vocabulary is that each rule can be stated clearly and concisely. With our example, we need

only seven simple rules:

Encode the specific instanceThe circuit shown in Figure Previous slide is encoded as circuit C1 with the following description. First, we categorize the gates:

Then, the connections between them:

Pose queries to the inference procedureWhat combinations of inputs would cause the first output of C1 (the sum bit) to be off and the second output of C1(the carry bit) to be on?