The following position has only eight pieces on the board with Black to move, but it is very tricky. I started trials with my modest means (Houdini 6.02) and White won 3/3 times, but after very complicated lines. I went deep in one case at d= 31/126. Is the ending really won for White?

[FEN "1r6/8/1P1Q2k1/K2P4/N7/3q4/8/8 b - - 0 0"]
  • 2
    You can use chess software or a website (for example on lichess.org, go TOOLS -> SET UP BOARD POSITION) to set up a board position and it will tell you the FEN.
    – B.Swan
    Oct 10 '20 at 14:31
  • 2
    Instead of taking the time to explain us how you "aren't expert in FEN lines", you could have taken the time to convert your position into FEN
    – David
    Oct 10 '20 at 19:59
  • 1
    @RewanDemontay By clicking into "edit" and viewing the FEN I was able to find out that the white pawns are moving down the board, i.e., the diagram is upside down. When I was young, we didn't have to guess which way the pawns were moving, chess diagrams were always printed with White moving up the board. That good idea seems to have been lost.
    – bof
    Oct 11 '20 at 2:50
  • I tried to go as far as d= 35/116. Then I analyzed the position after 13 moves and went as far as d= 32/98 the second time. It seems a White win , but it is very complicated. I still cannot be certain.
    – Stefano
    Oct 12 '20 at 5:20

Did Houdini use the 6-man databases? How did the first few moves go?

If Houdini could find nothing better for White than taking the Rook then it's a draw (given that White's pawns are moving down as stated in the comments). Wherever Black moves the King, the continuation Qxb8 Qxd5+ yields a database draw (presumably by perpetual check), and the same is true if White first checks on c7 or e5 and plays Qxb8 after Black returns to the sixth rank or goes to h4/g4.

  • I went as far as 38/128 (three quarters of an hour) and again it seems a White win. Obviously White do not take the rook so early.
    – Stefano
    Oct 12 '20 at 10:35
  • One possible win is WHITE King in c8 Queen in b8 Knight in c3 pawn in d5.BLACK King in g6 Queen in b4.BLACK to move. It is a mate in 59 for White but I had to control the tablebases separately because they are not incorporated into Houdini 6.02.
    – Stefano
    Oct 12 '20 at 11:03

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