[Retros] Natch 3.0 beta is out

Pascal Wassong pascal.wassong at free.fr
Fri Jul 29 14:45:09 EDT 2016 

Hi again :)

no, Natch cannot help.  This is a classical retro, not a shortest proof
game.  Natch is absolutely not done to answer your question.

The number of games to reach your position with the shortest number of
moves are by millions.  Even if Natch would give all these games (which
would take years), you still would have to check that in all games, the
bK has moved.

It is easy (at least for me !) to see that in your position, the bK must
have moved, so the black castling is illegal in this position.  The
proof is not very complicated to write down in plain english.  You
should do it, as this is generally printed with the solution.

There are many problems of this kind already existing.  This is a very
old trick, maybe 100 years old.

Pascal



>>>>> "Paulo" == Paulo Peccin <ppeccin at gmail.com> writes:

  Paulo> That is my initial position:
  Paulo> 4k2r/pp2p1p1/P7/4Np2/1B4Q1/P2NP1n1/1PbP3q/K2R3R

  Paulo> The idea is to prove that the Black King has moved and cannot
  Paulo> castle anymore.  Can Natch help in any means?

  Paulo> Thanks,


  Paulo> On Fri, Jul 29, 2016 at 3:25 PM, Pascal Wassong
  Paulo> <pascal.wassong at free.fr>
  Paulo> wrote:

  >> Hi Paulo,
  >> 
  >> Natch is absolutely not done to solve this kind of problems.  It
  >> will take way too much time, and spit out way too much solutions.
  >> 
  >> Checking if your initial position is legal is easy for anybody used
  >> to solve retrograde problems.  Finding the shortest proof game to
  >> your position is probably not interesting at all.  About 80 or 100
  >> years ago, this was sometimes done to show that a position is
  >> legal.  Nowadays, nobody does it anymore.
  >> 
  >> If you intend to publish your problem, the section editor where you
  >> will send it will be able to tell you if your position is legal or
  >> not.
  >> 
  >> Pascal
  >> 
  >> 
  >> >>>>> "Paulo" == Paulo Peccin <ppeccin at gmail.com> writes:
  >> 
  Paulo> Its for a problem I invented. Its a "mate in 2" problem that
  Paulo> requires retro analysis, and I want to check if the starting
  Paulo> position is really reachable in a normal valid game. So I don't
  Paulo> really know how many moves it would require to get there. I
  Paulo> want to find the minimum number of moves possible.
  >> 
  Paulo> Thanks, Paulo
  >> 
  >> 
  Paulo> On Fri, Jul 29, 2016 at 3:03 PM, Pascal Wassong
  Paulo> <pascal.wassong at free.fr>
  Paulo> wrote:
  >> 
  >> >> Hello,
  >> >>
  >> >> thank you for using iNatch and Natch !
  >> >>
  >> >> For iNatch, the version 0.7 has been created for 32 bits
  >> machines, >> this is a bit outdated.  I suggest using the previous
  >> version >> 0.6.2, which is a full java version, independant from 32
  >> bits or 64 >> bits.  Many users (me included) prefer the 0.6.2
  >> version.
  >> >>
  >> >> For Natch, you must provide the number of moves.  It is strange
  >> to >> want to try Natch on a position without knowing the minimum
  >> number >> of moves needed to reach it.  You could test the position
  >> while >> increasing the number of moves at each try.
  >> >>
  >> >> Best wishes, Pascal
  >> >>
  >> >>
  >> >>
  >> >> >>>>> "Paulo" == Paulo Peccin <ppeccin at gmail.com> writes:
  >> >>
  Paulo> Tried to run iNatch, but it does not start in my machine. Java8
  Paulo> installed.  The logs say:
  >> >>
  Paulo> !ENTRY org.eclipse.osgi 4 0 2016-07-29 14:45:04.760 !MESSAGE
  Paulo> Application error !STACK 1 java.lang.UnsatisfiedLinkError: no
  Paulo> swt-win32-3320 or swt-win32 in swt.library.path,
  Paulo> java.libary.path or the jar file
  >> >>
  Paulo> Also, can I use Natch to find a solution to a position, but I
  Paulo> don't know how many moves it would take to get to that
  Paulo> position?
  >> >>
  Paulo> Thanks, Paulo
  >> >>
  Paulo> On Fri, Jul 29, 2016 at 1:46 PM, Pascal Wassong
  Paulo> <pascal.wassong at free.fr>
  Paulo> wrote:
  >> >>
  >> >> >> Hello all,
  >> >> >>
  >> >> >> 19 years after the first version, 7 years after the latest >>
  >> version, >> a new version of Natch is out.  It is version 3.0 beta.
  >> >> You can >> download it from http://Natch.free.fr .
  >> >> >>
  >> >> >> Previous version already computed the order of some moves.
  >> This >> >> was used to eliminate position having cycles in it.  For
  >> example >> >> Pa2-a8=N-b6*Pa7 and Pa7xb6.  These move orders found
  >> for a >> position >> are now used when searching for the moves.
  >> For >> example, if black >> must play Rh8-e8-e3-c3 and white
  >> Pe2-e4, the >> wPe2 won't be allowed >> to move before the black
  >> rook arrived at >> c3.  This improvement >> increase the speed of
  >> resolution of many >> problems, and makes the >> --watch (-k for
  >> short) preaty useless.
  >> >> >>
  >> >> >> Many more move orders are also found.
  >> >> >>
  >> >> >> A bug has been corrected, where some solutions where not
  >> found.
  >> >> >>
  >> >> >> A bug has been corrected on Mac, which made the program crash
  >> >> when >> the hash-tables where full.  I was surprised to learn
  >> about >> this >> problem so late.
  >> >> >>
  >> >> >> There are also minor changes in the output file and when
  >> using >> the >> visual option.
  >> >> >>
  >> >> >> More details about this new version are available in the NEWS
  >> >> file >> available when you download the beta version.
  >> >> >>
  >> >> >> There were many bugs in the numerous alpha version while >>
  >> developing >> this 3.0 version, which have been found by the >>
  >> testers, mainly >> Michel Caillaud and Thierry Le Gleuher.  Thanks
  >> >> to them and to the >> other testers.
  >> >> >>
  >> >> >> There may still be bugs in this version.  If you find one,
  >> don't >> >> hesitate to send it to me.  The informations needed
  >> are: - the >> >> proof game, being as short as possible, that
  >> reproduces the bug; >> - >> the expected solution; - the number of
  >> the position where the >> bug >> occurs, if needed; - a clear
  >> description of what is going >> wrong.
  >> >> >>
  >> >> >> The precompiled version for windows is a 64 bits version.  I
  >> >> could >> also prepare a 32 bits windows version, if enough
  >> people >> are >> interested.
  >> >> >>
  >> >> >> Happy composing, Pascal >> >>
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