No.1299 (AO)

Алексей Оганесян (Россия)

Оригинальные Retro & PG задачи
JF – R2017-18

No.1299 Aleksey Oganesjan

original – 22.05.2018

Solutions: (click to show/hide)

white Ke1 Rh1 Bd3e5 Pd2f6h5h7 black Kh6 Bg8 Pf7g4g5

#1     b) Ke1→f5 ; c) Kh6→f3    (8+5)

23 комментария: No.1299 (AO)

  1. Ladislav Packa пишет:

    Something is wrong, maybe wPe2 should be on d2.
    This is a type of problem that can be labeled as “lost”. They are not orthodox, and there is too little retro. I know this from my own practice, publishers have the problem to find the right column for them …

  2. Dmitri TurevskiDmitri Turevski пишет:

    Are the “rotational” twins (as intended in P0000424) really inferior compared to the twins where thematic pieces (here – both kings) are displaced?

    • Aleksey Oganesjan пишет:

      In general – no, “rotational” twins are not inferior, of course. But concretely in P0000424, its heavy construction with many little-used units makes a bad impression, to my taste…

      • Dmitri TurevskiDmitri Turevski пишет:

        In P0000424 the only missing white piece is wBf1.
        This means that
        1) Last moves could not be dxe3/dxe5
        2) wBb8 is not promoted, and the check was given by the battery Rd6-f6+, which, in turn, leaves out the possibility of e6-e5, so the only possible last move is e7-e5.

        I could be wrong, please correct me if so, but this concept seems to naturally require 15 white men on board.

  3. Aleksey Oganesjan пишет:

    >> this concept seems to naturally require 15 white men on board.

    I think so: if one or several officers/pawns was set only for “retro-legality” of position and not for active participance in the play or in the mate, – then it is not very good.
    In P0000424 some white pawns are not need at all for the play and need only for that a quantity of white units equals 15 (for “retro-legality” – for impossibility of 0…dxe3/dxe5).

    >> In P0000424 the only missing white piece is wBf1.

    I means the following:

    P0000424 – 6 white pieces:
    a) 3/6 pieces are need for the play (and Qg8, Sh7, Rh1 are NOT need. I count Rf6 as necessary for the play because it provides e.p.);
    b) 3/6 pieces are need for the play (and Qg8, Rf6, Bb8 are NOT need);
    c) 2/6 pieces are need for the play (Rf6, Rh1, Sh7, Bb8 are NOT need).
    3/6 + 3/6 + 2/6 = 1,33 instead ideal 3 (44 %)

    My problem – 3 white pieces:
    a) 2/3 pieces are need for the mate (and Be5 is NOT need);
    b) 2/3 pieces are need for the mate (and Bd3 is NOT need. I count Be5 as necessary for the play because it provides e.p.);
    c) 3/3 pieces are need for the mate.
    2/3 + 2/3 + 3/3 = 2,33 instead ideal 3 (78 %)

    And we see: total loading of white pieces is equal 44 and 78 % respectively.
    It was a minute of math in this site :))

  4. Vlaicu Crisan пишет:

    Interesting to compare with another Valladao composition from more than 20 years ago with the stipulation ‘Last move?’ – see P0006515.

  5. GanapathiGanapathi пишет:

    diag. Last move 1.d4:e3 ep after Whites e2-e4
    b)) 1.0-0
    But what is the move in c)?

  6. GanapathiGanapathi пишет:

    Thanks, Ladislav Packa!

    • Seetharamanseetharaman пишет:

      In Isardam only way for black to check with Ba8 is to capture a white bishop on d1 (because white’s other possible last move e2-e4 illegal)
      So the last move was c2:Bd1=S.

  7. Geoff Foster пишет:

    Clever! In all parts the wK is in an apparently illegal check. (a) uses the en passant trick, in (b) the bBa8 has become observed by bRf8 through castling, while in (c) a wBd1 would prevent Bxf3 because of Isardam.

  8. Geoff Foster пишет:

    Is the bPf5 needed so that in (c) Pe2-e4 is illegal? According to Popeye the move Pe2-e4 is illegal anyway, because the wPe4 is observed “en passant” by the bPd4. That is, there is no need for the observation to be mutual.

  9. Geoff Foster пишет:

    This problem is more subtle than I realised!

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