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Re: Euro's and Dollars.

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In article <4fe0bd9f$0$9525$9b4e6d93@newsspool1.arcor-online.net>,
A. K. <akk@nospam.org> wrote:
>On 19.06.2012 17:58, Albert van der Horst wrote:
>> In article <20120619092656.0d5cc45a@tiger.support.j.intershop.de>,
>> Ecki  <ecki@intershop.de> wrote:
>>>> Someone said, CP is the most underestimated area in the software
>>>> industry.
>>>
>>> For Prolog, it's IMHO somehow the missing part, as it allows one to
>>> "semi-bind" a variable, in contrast to either have it bound or
>>> full-free. That in turn heavily reduces the possible search tree for
>>> many problems, making them solvable with much less effort or at all --
>>> think of how Sudoku is solved.
>>
>> The most natural way to solve a Sudoku is:
>>     for all unsolved squares find out how many possibilities it has.
>>     for all squares with 1 possibility fill it in
>>     repeat
>>
>
>You are thinking algorithmically. But CP is data driven and requires a
>fundamentally different mindset.
>
>F.ex. below is a _complete_ working plain vanilla straightforward
>generic Sudoku solver in BProlog. Non-optimized. It contains _only_
>range and position information, and the rules of the game. Nothing else.
>
>
>/* ##########
>Sudoku solver
>*/
>
>:- initialization(main).
>
>main :-
>
>Vars = [  % the board
>X11,X12,X13, X14,X15,X16, X17,X18,X19,
>X21,X22,X23, X24,X25,X26, X27,X28,X29,
>X31,X32,X33, X34,X35,X36, X37,X38,X39,
>
>X41,X42,X43, X44,X45,X46, X47,X48,X49,
>X51,X52,X53, X54,X55,X56, X57,X58,X59,
>X61,X62,X63, X64,X65,X66, X67,X68,X69,
>
>X71,X72,X73, X74,X75,X76, X77,X78,X79,
>X81,X82,X83, X84,X85,X86, X87,X88,X89,
>X91,X92,X93, X94,X95,X96, X97,X98,X99 ],
>Vars :: 1..9,
>
>sudoku(Vars),  % read in puzzle
>
>%row rules
>alldifferent([X11,X12,X13, X14,X15,X16, X17,X18,X19]),
>alldifferent([X21,X22,X23, X24,X25,X26, X27,X28,X29]),
>alldifferent([X31,X32,X33, X34,X35,X36, X37,X38,X39]),
>alldifferent([X41,X42,X43, X44,X45,X46, X47,X48,X49]),
>alldifferent([X51,X52,X53, X54,X55,X56, X57,X58,X59]),
>alldifferent([X61,X62,X63, X64,X65,X66, X67,X68,X69]),
>alldifferent([X71,X72,X73, X74,X75,X76, X77,X78,X79]),
>alldifferent([X81,X82,X83, X84,X85,X86, X87,X88,X89]),
>alldifferent([X91,X92,X93, X94,X95,X96, X97,X98,X99]),
>
>%column rules
>alldifferent([X11,X21,X31, X41,X51,X61, X71,X81,X91]),
>alldifferent([X12,X22,X32, X42,X52,X62, X72,X82,X92]),
>alldifferent([X13,X23,X33, X43,X53,X63, X73,X83,X93]),
>alldifferent([X14,X24,X34, X44,X54,X64, X74,X84,X94]),
>alldifferent([X15,X25,X35, X45,X55,X65, X75,X85,X95]),
>alldifferent([X16,X26,X36, X46,X56,X66, X76,X86,X96]),
>alldifferent([X17,X27,X37, X47,X57,X67, X77,X87,X97]),
>alldifferent([X18,X28,X38, X48,X58,X68, X78,X88,X98]),
>alldifferent([X19,X29,X39, X49,X59,X69, X79,X89,X99]),
>
>%block rules
>alldifferent([X11,X12,X13, X21,X22,X23, X31,X32,X33]),
>alldifferent([X14,X15,X16, X24,X25,X26, X34,X35,X36]),
>alldifferent([X17,X18,X19, X27,X28,X29, X37,X38,X39]),
>alldifferent([X41,X42,X43, X51,X52,X53, X61,X62,X63]),
>alldifferent([X44,X45,X46, X54,X55,X56, X64,X65,X66]),
>alldifferent([X47,X48,X49, X57,X58,X59, X67,X68,X69]),
>alldifferent([X71,X72,X73, X81,X82,X83, X91,X92,X93]),
>alldifferent([X74,X75,X76, X84,X85,X86, X94,X95,X96]),
>alldifferent([X77,X78,X79, X87,X88,X89, X97,X98,X99]),
>
>labeling(Vars),  % get solution
>writeln(Vars).
>
>% #####################################################################
>
>sudoku([  % Puzzle example
>8,6,7,  _,_,5,  9,1,_,
>1,_,_,  _,7,_,  _,8,5,
>_,3,_,  _,_,_,  _,_,_,
>
>_,_,_,  7,6,2,  1,_,_,
>_,8,_,  _,9,_,  _,6,_,
>_,_,2,  8,1,4,  _,_,_,
>
>_,_,_,  _,_,_,  _,3,_,
>9,1,_,  _,3,_,  _,_,6,
>_,4,3,  1,_,_,  8,2,9
>]).
>
>% that's all folks
>


Of course, but Prolog was made for this kind of problems.

From the procedural side I was impressed with Python.
After I solved it for 3 by 3 by 3, I discovered that I could
reuse the very same code for 4 by 4 by 4 with not much more then
changing a few boundaries.
Of course nobody expects your code as is is to be reusable for 4 by 4
by 4, but I even doubt you could come close to anything resembling
reusable classes.

Groetjes Albert

--
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst

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Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-18 19:00 +0000
  Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-18 23:18 +0200
    Re: Euro's and Dollars. Mark Wills <markrobertwills@yahoo.co.uk> - 2012-06-19 00:20 -0700
      Re: Euro's and Dollars. "Elizabeth D. Rather" <erather@forth.com> - 2012-06-18 21:51 -1000
  Re: Euro's and Dollars. vandys@vsta.org - 2012-06-19 00:49 +0000
    Re: Euro's and Dollars. Spam@ControlQ.com - 2012-06-18 21:43 -0400
      Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-19 07:20 +0200
        Re: Euro's and Dollars. Ecki <ecki@intershop.de> - 2012-06-19 09:26 +0200
          Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 15:58 +0000
            Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-19 19:58 +0200
              Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-20 01:31 +0000
                Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-20 07:15 +0200
            Re: Euro's and Dollars. Ecki <ecki@intershop.de> - 2012-06-20 10:15 +0200
            Re: Euro's and Dollars. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-20 10:46 +0000
              Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-20 17:39 +0000
                Re: Euro's and Dollars. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-21 16:21 +0000
                Re: Euro's and Dollars. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-21 11:58 -0500
                Re: Euro's and Dollars. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-22 14:57 +0000
                Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-21 20:38 +0000
      Re: Euro's and Dollars. vandys@vsta.org - 2012-06-19 15:49 +0000
    Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 15:43 +0000
      Re: Euro's and Dollars. vandys@vsta.org - 2012-06-19 15:51 +0000
  Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 15:41 +0000
    Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 10:26 -0700
      Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 23:34 -0700
    Re: Euro's and Dollars. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-19 12:41 -0500
      Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 11:10 -0700
        Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-20 03:12 +0000
          Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 23:51 -0700
        Re: Euro's and Dollars. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-20 03:15 -0500

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