[Retros] Fwd: FW: How many different positions?
grol33 at gmail.com
Mon Jan 14 12:19:40 EST 2019
Geurt is right (about only losing castling right after actually playing
..Ke7) and wrong (about being unhappy with it). One should be very happy
not having to evaluate whether or not castling right will be necessarily
lost in the future. In some positions such an evalution may be very
complicated and you want the game rules to be as simple as possible. When
you are very strict, you can claim there is never a certainty that a player
will lose castling right since he may resign raher than submit to playing
I hope Andrew Buchanan will clarify this in his proposals for new rules and
also explain the difference between castling and en passant in this respect.
On Wed, Jan 2, 2019 at 8:07 PM joose norri <joose_norri at hotmail.com> wrote:
> Geurt Gijssen discussed the second question in New in Chess 2/1987,
> referring to the famous Karpov-Miles 1986 and particularly Hartoch-Timman
> In that game, could white have claimed a draw before 21.Rf5? Announcing
> that he is playing Nc7. Geurt's position is that the rules at the time say
> that Black only loses castling rights when he actually plays Ke7. He seems
> unhappy with that.
> *Subject:* Re: [Retros] Fwd: FW: How many different positions?
> Olavi Riihimaa published the same position, except a4<>b4, d4<>e4, g4<>h4,
> in the British Chess Magazine November 1954, see also Schach und Zahl. He
> arrived at 192 positions.
> As to your second question, Olli Heimo constructed a position with I
> believe something like wKe1 Rh1 - bKe8 pe2, where obviously white can never
> castle, even though he hasn't lost the right to do so.
> Subject: FW: How many different positions?
> Date: Wed, 2 Jan 2019 11:21:20 +0000
> From: Mestel, Jonathan
> Sent: 02 January 2019 11:20
> To: The Retrograde Analysis Mailing List <retros at janko.at>
> Subject: How many different positions?
> Happy New Year All.
> Someone must have done this before. How many different positions can look
> the same? We define two positions which are identical in appearance as
> different if a sequence of moves could occur in one but not the other, so
> that castling or en passant rights may lead to different positions. For
> example, the attached position 3k2r/8/8/pPppPppP/pPPpPPpP/8/8/R3K2R I
> could represent 200 different positions:
> 192 = 4 * 4 * 6 * 2 = (White castling)*(Black castling)*(en
> Then change a1 to h8 and add 2*4 = (whose move)*(en passant)
> Giving a nice round total of 200. Is this maximal?
> And a related question. According to the current 3fold repetition rules of
> Fide, in the game
> 1 e4 d6 2 Bc4 f6 3 Bf7 Kd7 4 Bd5 Ke8 5 Bf7 Kd7 6 Bb3 Ke8 can White claim a
> draw on the grounds he intends to play 7 Bf7 ? The 3 positions are not
> identical in the sense that in the first Black could castle, and yet
> obviously no legal continuation would enable him to castle. So the
> positions are logically the same.
> Best wishes,
> Jonathan Mestel
> Professor of Applied Mathematics
> Imperial College London SW7 2AZ
> Huxley Building 746
> j.mestel at ic.ac.uk<mailto:j.mestel at ic.ac.uk <j.mestel at ic.ac.uk>>
> Retros mailing list
> Retros at janko.at
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