CSci 105

Introduction to Computers

Lecture 28

© Morris Firebaugh


I. Introduction

A. Continue Chapter 17 - The Cutting Edge: Expert Systems

B. Robotics

C. Critiques of the Turing Test

D. Examples of AI Programs


II. Expert Systems

Consider possible classes of Sailboats

Figure 13-3 Sailing Craft Identified by Expert System These nine vessels with their sail plans are uniquely identified by clues the user provides the expert system in an interactive query system. [From Firebaugh, M., Artificial Intelligence, Boyd & Fraser (1988)]


Using 17 IF-THEN Rules such as the following:

The Expert System uses the following dialog to produce the result:




Examples of Expert Systems


III. Robotics

Consider the definition suggested by the Robotics Industries Association:


Figure 16-2 T3 – An articulated robot with 6 Degrees of Freedom Note that 6 degrees of freedom are required for completely generalized motion. Three degrees are required for position and three for orientation. [From Firebaugh, M., Artificial Intelligence, Boyd & Fraser (1988)]


What should robots do?

IV. Critiques of the Turing Test

Turing's own objections to AI

1. The Theological Objection --> "Thinking is a function of man's immortal soul." Turing refutes the above argument by noting: "It appears to me that the argument quoted above implies a serious restriction of the omnipotence of the Almighty. That is, could God have not given a soul to an elephant or a machine had he wanted to?"

2. The "Heads In The Sand" Objection --> "The consequences of machines thinking would be too dreadful. Let us hope and believe that they cannot do so." Turing notes that this objection "... is likely to be quite strong in intellectual people, since they value the power of thinking more highly than others ," but then dismisses it as insufficiently substantial to require refutation.

3. The Mathematical Objection --> (Gödel's Theorem) " in any sufficiently powerful logical system, statements can be formulated which can neither be proved nor disproved within the system, unless possibly the system itself is inconsistent." Turing acknowledges the validity of this argument, noting that he himself had published similar results. He then observes that there is no proof that the human intellect does not suffer the same limitations and concludes, "We too often give wrong answers to questions ourselves to be justified in being very pleased at such evidence of fallibility on the part of the machines."

4. The Argument From Consciousness --> "Not until a machine can write a sonnet or compose a concerto because of thoughts and emotions felt, and not be a chance fall of symbols, could we agree that machine equals brain - that is, not only write it but know that it had written it." This argument leads to the classical solipsist position that the only way to know how a person thinks is to be that person. Rather than get into the endless circular arguments into which such a position leads, Turing notes that "... it is usual to have the polite convention that everyone thinks."

5. Arguments From Various Disabilities --> "I grant you that you can make a machine do all the things you have mentioned, but you will never be able to make one to do X" where X is the ability to "be kind, resourceful, beautiful, friendly, like ice cream." Turing refutes this argument by correctly observing that "Many of these limitations are associated with the very small storage capacity of most machines." Perhaps it is significant that increased memory capacity has facilitated the feature we call "user friendliness" in modern operating systems.

6. Lady Lovelace's Objection --> "The Analytical Engine has no pretensions to originate anything. It can do whatever we know how to order it to perform." Another version of this objection states: "Machines never do anything really new" or can never "take us by surprise." Turing says, "Machines take me by surprise with great frequency." Most of us who program certainly share this experience.

7. Arguments from Continuity of the Nervous System --> "The nervous system is certainly not a discrete state machine." Since small errors in the size of an impulse striking a neuron may make a large difference in the size of the outgoing impulse one cannot expect to mimic the behavior of the nervous system with a discrete state system. Turing fails to offer a convincing rebuttal to this argument, but we should note that present day computers can simulate the behavior of non-linear, analog devices for which the transformation is known, to almost any desired accuracy by standard computational procedures. This argument, however, is the central tenet of those working in the field of neural network research as the basis for the validity of their approach.

8. The Argument from Informality of Behavior --> "It is not possible to produce a set of rules purporting to describe what a man should do in every conceivable set of circumstances." For instance, if a red light means "stop" and a green light means "go," what would a computer do when faced with a simultaneous red and green light due to a fault in the system? This is a tough argument to refute, but Turing suggests that we can experimentally determine the "laws of behavior" (as opposed to the "rules of conduct") which may be able to resolve such dilemmas.

9. The Argument from Extrasensory Perception --> Here Turing cites four manifestations of extrasensory perception: telepathy, clairvoyance, precognition, and psychokinesis and sadly notes, "How we should like to discredit them! Unfortunately the statistical evidence, at least for telepathy, is overwhelming." Here at last Turing has blundered in interpreting telepathy as a valid phenomenon. The "overwhelming statistical evidence" has evaporated like the morning mist exposed to the harsh sunlight of full disclosure and independent confirmation. It is tempting to criticize Turing for not having the courage of his convictions, but we might note that many great scientists have had at least one faux pas. Maxwell refers to the "luminiferous ether" as the medium for his light waves. Einstein did not accept the statistical interpretation of quantum theory ("God does not play dice with the Universe!"), and Enrico Fermi observed both the neutron and nuclear fission but failed to discover them.


V. Examples of AI Programs

Example 1: Continuous Speech, User-Independent Voice Recognition


Example 2: A Neural Network that Learns to Recognize Letters


Activites after 25 Cycles

Activites after 50 Cycles

Activites after 161 Cycles



Example 3: The Deep Blue Chess Program


"For me, the match was over yesterday. I had no real strength left to fight. And today's win by Deep Blue was justified."


VI. Laboratory Assignment # 14

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Updated November 27, 2000