# [Retros] Natch 3.0 beta is out

Paulo Peccin ppeccin at gmail.com
Fri Jul 29 14:52:41 EDT 2016

```Ok, I see...  :-)

I'm very newbie to all this retro analysis, and not very literate to chess
in general.

That is a problem a friend of mine and I have invented, without even
knowing there was an established "retro" type of problems.

I have written a solution with proof in english for the problem, but I am
just trying to find a means to "prove the proof", with some kind of
computer help...

Thanks anyway!
Paulo

On Fri, Jul 29, 2016 at 3:45 PM, Pascal Wassong <pascal.wassong at free.fr>
wrote:

> Hi again :)
>
> no, Natch cannot help.  This is a classical retro, not a shortest proof
>
> 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.
>   >> >> >>
>   >> >> >> 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.
>   >> >> >>
>   >> >> 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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