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Article 4387 of comp.ai.philosophy:
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>From: santas@inf.ethz.ch (Philip Santas)
Newsgroups: comp.ai.philosophy
Subject: Re: Definition of understanding
Message-ID: <1992Mar11.122705.22342@neptune.inf.ethz.ch>
Date: 11 Mar 92 12:27:05 GMT
References: <1992Mar2.214012.22715@psych.toronto.edu> <1992Mar10.143639.10130@neptune.inf.ethz.ch> <1992Mar10.171755.7458@psych.toronto.edu>
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In article <1992Mar10.171755.7458@psych.toronto.edu> michael@psych.toronto.edu (Michael Gemar) writes:
>In article <1992Mar10.143639.10130@neptune.inf.ethz.ch> santas@inf.ethz.ch (Philip Santas) writes:
>>michael@psych.toronto.edu (Michael Gemar) writes:
>>>
>>>PE = 1/2 k x^2
>>>
>>>where PE = potential energy
>>>       k = spring constant
>>>       x = displacement from equilibrium
>>>
>>>You do so as a purely mechanical operation.  If asked, he would answer
>>>that he knows nothing about potential energy, or spring constants, or
>>>the like.
>>>
>>>You then say, "Aha, but the *system* that calculates potential energy
>>>in a spring does!"  However, someone who knows electrostatics says,
>>>"But wait!  That's also the formula for calculating the electrostatic
>>>energy *in a capacitor*.  Simply *interpret* k as C (capacitance) and
>>>x as V (potential across the capacitor plates)."  *Now* what does the
>>>system "understand"?  Only pendulums?  Only capacitors?  Pendulums *and*
>>>capacitors?  I'd vote for neither, myself.
>>
>>If the system has as input only the mathematical formula, it is
>>possible that you get a variety of solutions according to the input.
>>k can be number of number of cars, and x anything else.
>>The human or the computer needs the definitions that you add after the
>>formula. This means that we talk about mechanical and not electrical
>>energy.
>
>How do you give definitions that have semantic content to a computer?
>How does it know that when you respond to the request "Please input
>the capacitance constant => " that you are talking about capacitance,
>and not number of cars?  The problem of generating "definitions" with
>semantic content for a computer *is* the central problem under discussion.

You can do type checking even statically in this example:

  PE GivePE(Distance displacementFromEquilibrium)
          {
           Distance x = displacementFromEquilibrium;
           SpringConstantType k = SpringConstant;    // this is global variable 
           return (1/2) * k * power(x,2);
          };

Relevant things you can do for capacitances, by changing the type
of the argument displacementFromEquilibrium.

>>Your formula itself does not refer to capacitors either. It is the set
>>of definitions of the variables that clear things up
>
>Agreed.  But I do not see a way of providing variable definitions that would
>"clear things up" from the point of view of the computer.

Notice that EVEN languages like C++ have such abilities...

Philip Santas

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