Re: LOGO-L> Logical Puzzle

["Olga Tuzova" <olgatu@ort.spb.ru>]

On  Mon, 12 Jan 1998  George Mills  wrote:

> This is Brian's cup of tea, if you will.
> 
> Check out MSWLogo\Examples\UCBLogo\Math.LGO
> 
> This is also what Prolog is all about (that was discussed a while back).
> Note that you can define Math itself as logic problems as well.

Thank you, George, somehow I've missed this. The "Brian's cup of 
tea" is really very powerful, it's great, but it's power costs 
some complexity. I should look at it more attentively, but I don't 
think, I could use it for my students, or at least begin with it.

As to Prolog, it's out of our curriculum. I'm just interested in how  
Logo could be implemented there. I agree to the principle -- right 
tool in the right place, but I think, Logo fits this problem well.

Regards,
Olga.

> 
> Olga Tuzova wrote:
> > 
> > Hello everybody,
> > 
> > I'm intruding on your recursion discussion with very different problem.
> > I haven't seen this kind of problems there, but may be somebody is
> > interested, or has had an experience in solving them.
> > The problem is from a "logical field".
> > 
> > For example let's formulate it as follows.
> > 
> > Three experts are having discussion about an ancient cup.
> > 
> > Expert A: This is a China cup from the 5th century,
> > Expert B: This is a Japan cup from the third century,
> > Expert C: This is not a China cup, it was made in the 4th century.
> > 
> > It turned out, only one of two statements of each expert was right, the
> > other was wrong.
> > 
> > What country and what century does the cup belong?
> > ----------------
> > 
> > I think, the main idea of the solution is standart.
> > 
> > Le's denote with C the statement "the cup is from China",
> >             J - "from Japan",
> >             T - "it was made in the third century",
> >             F - " in the 4th century",
> >             V - " in the 5th century".
> > 
> > We should find such boolean values of C J T F V, which make the
> > following statements  "true":
> >     or (and C not V)(and not C V)
> >     or (and J not T)(and not J T)
> >     or (and not not C F)(and not C not F)
> > Also:
> >     not and T F
> >     not and T V
> >     not and F V
> >     not and C J.
> > 
> > The solutions that I've seen, all use looking over(?) all the possible
> > combinations of values of C, J, T, F, V. It doesn't look great. I tried
> > to present these combination as a binary code (binary representation of
> > the number from 0 through 31), but not sure it improves the solution
> > much.
> > Would be greatful for any ideas and suggestions. Also, does anybody work
> > on such problems this way or other with the school children?
> > 
> > The solution presented below, says, that the cup was from Japan and was
> > made in the 5th century.
> > 
> > Thanks,
> > Olga.
> > ---------------------------------
> > to logic.main
> > for [i 0 31][if (and bool1 c :i v :i ~
> >                      bool1 j :i t :i ~
> >                      bool2 c :i f :i ~
> >                      bool3 c :i j :i ~
> >                      bool3 t :i f :i ~
> >                      bool3 t :i v :i ~
> >                      bool3 f :i v :i)~
> >             [(pr c :i j :i t :i  f :i v :i)]]
> > end
> > 
> > to c :i
> > op int :i/16
> > end
> > 
> > to j :i
> > op remainder int :i/8 2
> > end
> > 
> > to t :i
> > op remainder int :i/4 2
> > end
> > 
> > to f :i
> > op remainder int :i/2 2
> > end
> > 
> > to v :i
> > op remainder :i 2
> > end
> > 
> > to bool1 :c :v
> > output or (and l :c not l :v) (and l :v not l :c)
> > end
> > 
> > to bool2 :c :f
> > output or (and not not l :c l :f)(and not l :c not l :f)
> > end
> > 
> > to bool3 :c :j
> > output not and l :c l :j
> > end
> > 
> > to l :a
> > ifelse :a=1 [op "true][op "false]
> > end
> > -------------------------------
> > 
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