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   sci.math.symbolic      Symbolic algebra discussion      10,432 messages   

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   Message 9,851 of 10,432   
   bursejan@gmail.com to All   
   Re: Maxima .... Re: how does your CAS ha   
   07 Mar 18 11:39:02   
   
   Wolfram Alpha has the potential to react   
   like this, since its not only input -> program,   
   but rather input -> (?timely?) knowledgebase.   
      
   At least it looks like that from the    
   outside sometimes. So it all depends    
   what this should really mean:   
      
   "CAS attach that language to a set of programs   
   that have been written to solve a subset of   
   mathematical questions.  That subset may be   
   enlarged from time to time if systems are   
   improved." - RJF    
      
   Am Mittwoch, 7. März 2018 20:33:25 UTC+1 schrieb burs...@gmail.com:   
   > Maybe CAS should become AI, and we should send   
   > CAS programs to libraries, so they can read that   
   > fermats last problem was solved, and can return "no".   
   >    
   > Am Mittwoch, 7. März 2018 20:20:01 UTC+1 schrieb Richard Fateman:   
   > > On 3/7/2018 12:25 AM, Nasser M. Abbasi wrote:   
   > > >    
   > > > I am, as a CAS user, not being vague at all. I am simply using   
   > > > a CAS commands, provided by the CAS maker to use.   
   > > > Which is to do some computation under some assumptions.   
   > >    
   > >    
   > >    
   > > OK, here is a simple set of CAS commands:   
   > >    
   > > assume ([a,b,c,n], integers);   
   > > assume (n>2),   
   > >    
   > > solve (a^n+b^n=c^n,  [a,b,c,n]);   
   > >    
   > > nothing wrong with that?   
   > >    
   > > It would have saved Andrew Wiles and others (back to Fermat)   
   > > a lot of time if they had just typed those commands, or something   
   > > equivalent, into a CAS.   
   > >    
   > > Oh, but maybe those CAS had bugs?  Shame on them.   
   > >    
   > >    
   > >    
   > > The language of mathematics,  even when the language is   
   > > paraphrased into a constrained one-dimensional string of characters,   
   > > is sufficient to express problems that are   
   > >    
   > > ambiguous or nonsensical   
   > > paradoxical   
   > > computationally unsolvable.   
   > >    
   > > CAS attach that language to a set of programs   
   > > that have been written to solve a subset of   
   > > mathematical questions.  That subset may be   
   > > enlarged from time to time if systems are   
   > > improved.   
   > >    
   > > Asking a CAS to solve a problem for which it has   
   > > not been programmed is not difficult.  Just pick   
   > > a problem that does not fit in the programmed   
   > > algorithmic subset of the system. There is a   
   > > class of "CAS independent"   "bugs" that they   
   > > all get wrong.   
   > >    
   > > It is difficult to define exactly what each CAS subset is,   
   > > but even if it were defined carefully, I doubt that   
   > > (especially beginning) users would pay attention to it.   
   > >    
   > > Another approach would be to tightly constrain   
   > > the utterances that are possible in the user language.   
   > > This is a very useful tactic, used, for example,   
   > > in the designs of vending machines, bank ATMs,   
   > > or 10-key+operators  calculators.  Most (all?)   
   > > CAS designers have not followed this approach.   
   > >    
   > > A simple example that has come to mind recently   
   > > is how to treat "infinity".   
   > >    
   > > Just because you can utter and compute  limit(1/x^2,x,inf)  does   
   > > NOT mean "inf"  with all its mathematical baggage   
   > > is completely understood by a CAS.   
   > >    
   > > What is inf+inf?   inf^2?  inf-inf?  exp(i*inf)? sin(inf)?....   
   > > For that matter, humans disagree on what some   
   > > such utterances mean.   
   > >    
   > > So to return to my claim.  You can use a CAS to do what   
   > > they are programmed to do. Just because its input   
   > > language allows you to make some inquiry does   
   > > not mean the CAS can make sense of it and answer it.   
   > > If you want to get useful results from a CAS, you may need to   
   > > apply some thought.   
   > >    
   > > By analogy with cars, just because a car has a speedometer   
   > > that goes up to 120 miles per hour (i.e. about 200 kmph) does not mean that   
   > > it can actually go that fast.  Or that it is a good idea to try.   
   > > And the car odometer might have 6 digits, indicating that it will last   
   > >   999,999 miles (or km?).  but it might not.   
   > >    
   > > RJF   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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