University of Toronto, Department of Computer Science
CSC 485SF—Computational Linguistics, Summer 2020
Final assessment
Due date: Thursday 25 June 2020 at 11:59pm EDT.
Copyright By PowCoder代写 加微信 powcoder
Late write-ups will not be accepted without documentation of a medical or other emergency. This assessment is worth 10% of your final grade.
What to read
, “Computing machinery and intelligence”, Mind, 59, 1950, 433–460.
What to write
Briefly answer the following questions:
1. (2 marks) What is the “Turing test,” according to the viewpoint of an AI enthusiast in the year 2020?
2. (2 marks) What test did Turing originally propose in this 1950 article, and how does it differ from the answer to question (1)?
3. (6 marks) Pick one of the following topics that we covered this term:
• Syntax, Parsing, and Parse Disambiguation,
• Lexical Semantics (including Word-Sense Disambiguation), • Question Answering, or
• Anaphora Resolution.
Using only your chosen topic, how would you scrutinize a contestant in a 2020-style Turing Test? You should assume that a computer contestant is equipped with topic- related functionality that is the state of the art as of this year. You may also assume that you have unlimited access to corpora and, where necessary, annotation resources, so that any data that you may need to use or train on have already been prepared for you. But your scrutiny must be feasible using a contemporary HPC cluster, assuming a maximum one-month training and evaluation period (with corpora already in hand) that includes a maximum of five minutes of questioning the contestant, distributed over as many sessions as you like.
Some points to consider:
• Your job in question (3) is to impeach the credibility of a contestant, not to pose as or build a contestant.
• Turingwasaskingarelatedbutaltogetherdifferentquestion:“Couldamachinethink?”. You need not address this.
• A lot has been learned since 1950 about what machines can and cannot do. The re- search fields of artificial intelligence and machine learning have had many successes and failures.
General requirements: Your submission should be typed, using 12-point font and 1.5-line spacing; it should fit on one to two sides of a sheet of paper. Only the first two pages of what you submit shall be assessed.
Submit one file with your answers using the submit command on teach.cs:
% submit -c
where
Computing Machinery and Intelligence
A. M. Turing
Mind, , Vol. 59, No. 236. (Oct., 1950), pp. 433-460. Stable URL:
http://links.jstor.org/sici?sici=0026-4423%28195010%292%3A59%3A236%3C433%3ACMAI%3E2.0.CO%3B2-5
Mind is currently published by Oxford University Press.
Your use of the JSTOR archive indicates your acceptance of JSTOR’s Terms and Conditions of Use, available at http://www.jstor.org/about/terms.html. JSTOR’s Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use.
Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/journals/oup.html.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission.
JSTOR is an independent not-for-profit organization dedicated to and preserving a digital archive of scholarly journals. For more information regarding JSTOR, please contact
http://www.jstor.org Thu Apr 5 11:21:34 2007
A QUARTERLY REVIEW
PSYCHOLOGY AND PHILOSOPHY
I.-COMPUTING MACHINERY AND INTELLIGENCE
1. The Imitation Game.
I PROPOSE to consider the question, ‘ Can machines think ? ‘ This should begin with definitions of the meaning of the terms ‘machine’and’think’. Thedefinitionsmightbeframedsoasto reflect so far as possible the normal use of the words, but this attitude is dangerous. If the meaning of the words ‘ machine ‘ and ‘ think ‘ are to be found by examining how they are commonly used it is difficult to escaDe the conclusion that the meaninga and the answer to tlie auestion, ‘ Can machines think ? ‘ is to be sought in a statistical sirvey sdch as a Gallup poll. But this is absurd. Instead of attempting such a definition I shall replace the question by another, which is closely related to it and is expressed in relatively unambiguous words.
The new form of the problem can be described in terms of a game which we call the ‘ imitation game ‘. I t is played with three people, a man (A),a woman (B),and an interrogator (C)who may be of either sex. The interrogator stays in a room apart from the other two. The object of the game for the interrogator is to determine which of the other two is the man and which is the woman. He knows them by labels X and Y, and at the end of the game he says either ‘ X is A and Y is B ‘ or ‘ X is B and Y is A ‘. The interrogator is allowed to put questions to A and B thas :
C : please tell me the length of his or her hair ?
Now suppose X is actually A, then A must answer. It is A’s
[October, 1950
434 A. M. TURING :
object in the game to try and cause C to make the wrong identi- fication. His answer might therefore be
‘My hair is shingled, and the longest strands are about nine inches long.’
In order that tones of voice may not help the interrogator the answers should be written, or better still, typewritten. The ideal arrangeljaent is to have a teleprinter communicating between the two rooms. Alternatively the question and answers can be repeated by an intermediary. The object of the game for the third player (B) is to help the interrogator. The best strategy for her is probably to give truthful answers. She can add such things as ” I am the woman, don’t listen to him ! ‘ to her answers, but it will avail nothing as the man can make similar remarks.
We now ask the question, ‘ What will happen when a machine takes the part of A in this game ? ‘ Will the interrogator decide wrongly as often when the game is played like this as he does when the game is played between a man and a woman ? These questions replace our original, ‘ Can machines think ? ‘
2. Critique of the .
As well as asking, ‘ What is the answer to this new form of the question ‘, one may ask, ‘ Is this new question a worthy one to investigate ? ‘ This latter question we investigate without further adojthereby cutting short an infinite regress.
The new problem has the advantage of drawing a fairly sharp line between the physical and the intellectual capacities of a man. No engineer or chemist claims to be able to produce a material which is indistinguishable from the human skin. It is possible that at some time this might be done, but even supposing this in- vention available we should feel there was little point in trying to make a ‘thinking machine ‘ more human by dressing it up in such artificial flesh. The form in which we have set the problem reflects this fact in the condition which prevents the interrogator from seeing or touching the other competitors, or hearing their voices. Some other advantages of the proposed criterion may be shown up by specimen questions and answers. Thus:
Q : Please write me a sonnet on the subject of the Porth Bridge.
A : Count me out on this one. I never could write poetry.
Q : Add 34957 to 70764 .
A : (Pause about 30 seconds and then give as answer) 105621. Q : Do you play chess ?
COMPUTING MACHINERY AND INTELLIGENCE 435
Q : I have K at my K1, and no other pieces. You have only KatK6andRatR1. Itisyourmove. Whatdoyou play ?
A:(Afterapauseof 15seconds)R-R8mate.
The question and answer method seems to be suitable for introducing almost any one of the fields of human endeavour that we wish to include. We do not wish to penalise the machine for its inability to shine in beauty competitions, nor to penalise a man for losing in a race against an aeroplane. The conditioiis of our game make these disabilities irrelevant. The ‘ witnesses ‘ can brag, if they consider it advisable, as much as they please about their charms, strength or heroism, but the interrogator cannot demand practical demonstrations.
The game may perhaps be criticised on the ground that the odds are weighted too heavily against the machine. If the man were to try and pretend to be the machine he would clearly make a very poor showing. He would be given away a t once by slowness and inaccuracy in arithmetic. May not machines carry out some- thing which ought to be described as thinking but which is very different from what a man does ? This objection is a very strong one, but at least we can say that if, nevertheless, a machine can be constructed to play the imitation game satisfactorily, we need
not be troubled by this objection.
It might be urged that when playing the ‘imitation game ‘
the best strategy for the machine may possibly be something other than imitation of the behaviour of a man. This may be, but I think it is unlikely that there is any great effect of this kind. In any case there is no intention to investigate here the theory of the game, and it will be assumed that the best strategy 1s to try to provide answers that would naturally be given by a man.
3. The Machines concerned i n the Game.
The question which we put in 9 1 will not be quite definite until we have specified what we mean by the word ‘ machine ‘. I t is natural that we should wish to permit every kind of engineering technique to be used in our machines. We also wish to allow the possibility than an engineer or team of engineers may construct a machine which works, but whose manner of operation cannot be satisfactorily described by its constructors because they have applied a method which is largely experimental. Finally, we
wish to exclude from the machines men born in the usual manner. It is difficult to frame the definitions so as to satisfy these three conditions. One might for instance insist that t$e team of
436 A. M. TURING :
engineers should be all of one sex, but this would not really be satisfactory, for it is probably possible to rear a complete individual from a single cell of the skin (say) of a man. To do so would be a feat of biological technique deserving of the very highest praise, but we would not be inclined to regard it as a case of ‘ constructing a thinking machine ‘. This prompts us t o abandon the requirement that every kind of technique should be permitted. We are the more ready to do so in view of the fact that the present interest in ‘thinking machines ‘ has been aroused by a particular kind of machine, usually called an ‘ electronic computer ‘ or ‘ digital computer ‘. Following this suggestion we only permit digital computers to take part in our
This restriction appears at first sight to be a very drastic one.
I shall attempt to show that it is not so in reality. To do this necessitates a short account of the nature and properties of these computers.
It may also be said that this identification of machines with digital computers, like our criterion for ‘ thinking ‘, will only be unsatisfactory if (contrary to my belief), it turns out that digital computers are unable to give a good showing in the game.
There are already a number of digital computers in working order, and it may be asked, ‘ Why not try the experiment straight away ? It would be easy to satisfy the conditions of the game. A number of interrogators could be used, and statistics compiled to show how often the right identification was given.’ The short answer is that we are not asking whether all digital computers would do well in the game nor whether the computers at present available would do well, but whether there are imaginable com- puters which would do well. But this is only the short answer. We shall see this question in a different light later.
4.Digital Compute~s.
The idea behind digital computers may be explained by saying that these machines are intended to carry out any operations which could be done by a human computer. The human computer is supposed to be following fixed rules ; he has no authority to deviate from them in any detail. We may suppose that these rules are supplied in a book, which is altered whenever he is put on to a new job. He has also an unlimited supply of paper on which he does his calculations. He may also do his multiplications and additions on a ‘ desk machine ‘, but this is not important.
If we use the above explanation as a definition we shall be in
COMPUTING MACHINERY AND INTELLIGENCE 437
danger of circularity of argument. We avoid this by giving an outline of the means by which the desired effect is achieved. A digital computer can usually be regarded as consisting of three parts :
(i) Store.
(ii) Executive unit.
(iii) Control.
The store is a store of information, and correspondsto the human computer’s paper, whether this is the paper on which he does his calculations or that on which his book of rules is printed. In so far as the human computer does calculations in his head a part of the store will correspond to his memory.
The executive unit is the part which carries out the various individual operations involved in a calculation. What these individual operations are will vary from machine to machine. Usually fairly lengthy operations can be done such as ‘Multiply 3540675445 by 7076345687’ but in some machines only very simple ones such as ‘ Write down 0 ‘ are possible.
We have mentioned that the ‘book of rules’ supplied to the computer is replaced in the machine by a part of the store. It is then called the ‘table of instructions ‘. It is the duty of the control to see that these instructions are obeyed correctly and in the right order. The control is so constructed that this necessarily happens.
The information in the store is usually broken up into packets of moderately small size. I n one machine, for instance, a packet might consist of ten decimal digits. Numbers are assigned to the pads of the store in which the various packets of information are stored, in some systematic manner. A typical instruction might say-
‘ Add the number stored in position 6809 to that in 4302 and put the result back into the latter storage position ‘.
Needless to say it would not occur in the machine expressed in English. It would more likely be coded in a form such as 6809430217. Here 17 says which of various possible operations is to be performed on the two numbers. In this case the opera- tion is that described above, viz. ‘Add the number. . . .’ It will be noticed that the instruction takes up 10 digits and so forms one packet of information, very conveniently. The control will normally take the instructions to be obeyed in the order of the positions in which they are stored, but occasionally an in- struction such as
438 A. M. TURING :
‘Now obey the instruction stored in position 5606, and con- tinue from there ‘
may be encountered, or again
‘If position 4505 contains 0 obey next the instruction stored in 6707, otherwise continue straight on.’
Instructions of these latter types are very important because they make it possible for a sequence of operations to be repeated over and over again until some condition is fulfilled, but in doing so to obey, not fresh instructions on each repetition, but the same ones over and over again. To take a domestic analogy. Suppose Mother wants Tommy to call at the cobbler’s every morning on his way to school to see if her shoes are done, she can ask him
. afresh every morning. Alternatively she can stick up a notice once and for all in the hall which he will see when he leaves for school and which tolls him to call for the shoes, and also to destroy the notice when he comes back if he has the shoes with him.
The reader must accept it as a fact that digital computers can be constructed, and indeed have been constructed, according to the principles we have described, and that they can in fact mimic the actions of a human computer very closely.
The book of rules which we have described our human com~uter
as using is of course a convenient fiction. Actual human com- puters really remember what they have got to do. If one wants to make a machine mimic the behaviour of the human computer in some complex operation one has to ask him how it is done, and then translate the answer into the form of an instn~ctiontable. Constructing instruction tables is usually described as ‘pro- gramming ‘. To ‘ programme a machine to carry out the opera- tion A ‘ means to put the appropriate instruction table into the machine so that it will do A.
An interesting variant on the idea of a digital computer is a ‘digitalcomputerwitharandomelement’. Thesehaveinstructions involving the throwing of a die or some equivalent electronic process ; one such instruction might for instance be,’ Throw the die and put the resulting number into store 1000 ‘. Sometimes such a machine is described as having free will (though I would not
usethisphrasemyself). Itisnotnormallypossiblei;odetermine from observing a machine whether it has a random element, for a similar effect can be produced by such devices as making the choices depend on the digits of the decimal for T.
Most actual digital computers have only a finite store. There is no theoretical difficulty in the idea of a computer with an un- limited store. Of course only a finite part can have been used at any one time. Likewise only a finite amount can have been
COMPUTING MACHINERY AND INTELLIGENCE 439
oonstructed, but we can imagine more and more being added as required. Such computers have special theoretical interest and will be called infinitive capacity computers.
The idea of a digital computer is an old one. , Luca,sian Professor of Mathematics at Cambridge from 1828 to 1839, planned such a machine, called the Analytical Engine, but it was never completed. Although Babbage had all the essential ideas. his machine was not at that time such a verv attractive prospect. h he speed which would have been availabie would be definitely faster than a human computer but ~omet~hing like 100 times slower than the Manchester machine, itself one of the slower of the modern machines. The storage was to be
purely mechanical, using wheels and cards.
The fact that Babbage’s Analytical Engine was to be entirely
mechanical will help us to rid ourselves of a superstition. Import- ance is often attached to the fact that modern digital computers are electrical, and that the nervous system also is electrical. Since Babbage’s machine was not electrical, and since all digital com- puters are in a sense equivalent, we see that this use of olectri~it~y cannot be of theoretical importance. Of course electricity usually comes in where fast signalling is concerned, so that it is not surprising that we find it in both these connections. In the nervous system chemical phenomena are at least as important
as electrical. In certain computers the storage system is mainly acoustic. The feature of using electricity is thus seen to be only a very superficial similarity. If we wish to find such similarities we should look rather for mathematical analogies of function.
5. Universality of Digital Computers.
The digital computers considered in the last section may be classified amongst the ‘ discrete state machines ‘. These are the machines which move by sudden jumps or clicks from one quite definite state to another. These states are sufficientlv different for the possibility of confusion between them to be ignored. Strictly speaking there are no such machines. Everything really moves continuously. But there are many kinds of machine which can profitably be thought of as being discrete state machines. For instance in considerin
程序代写 CS代考 加微信: powcoder QQ: 1823890830 Email: powcoder@163.com