17th Southwest Class 2026 · 2026.02.16 · Elo 2506/2450 · interesting · ★★★★
The daily position for Sunday 27 September 2026. It is still open to solve — the grader reads your whole line, sidelines and evaluation included, before anything here is shown. Cover the solution and solve it first →
White to move. the model gives this to 1 in 5 at this level.
The solution
39.♖︎f7!△♖︎f8#(not39.♗︎c3?♗︎xc740.♖︎xc7♖︎d8⩱)39…♗︎c7(if39…d2then40.♖︎f8#)40.♖︎fxc7d241.♗︎e5♖︎d8(41…d1=♕︎+is as good:42.♔︎h2♖︎d843.♖︎g7++−)42.♖︎g7+♔︎f843.♖︎gf7++−
39.♖︎f7 — most players miss this · the threat is ♖︎f8# — what it plays next if the defence does nothing
40.♖︎fxc7 — the natural move
41.♗︎e5 — almost nobody finds this · worth +1
42.♖︎g7+ — the standard move
43.♖︎gf7+ — most players miss this · worth +1
“hard to find”, “the natural move” and the rest describe how often this move is played by Maia-2, weighted across the 1500/1900/2000 audience the difficulty model is fitted on — a model of human play, not a count of anyone who solved this position.
Members can take this away as a PGN — the diagram, the verified line and their own analysis in one file, for a database, Anki or Chessable.
What happened at the board
Avila Pavas found it · 1-0
the game went on39…♗︎a540.♗︎e5d241.♖︎g7+♔︎f842.♗︎d6+1-0full game ↗
The field
78% of the 9 committed lines here found the key move — the model predicted 19% at this level.