'Only One Move Keeps It Equal,' Says Man Who Found It After Pressing New Game

A rated rapid game ended Friday night and was posted to a public chess forum as a single-answer puzzle before the losing player had finished deciding which opening file to load next.

The post went up at 20:14 under the heading "Only one move keeps it equal." It showed a position from move 42 of a 15+10 game in the 1,700 to 1,800 pool, Black to move, white pawn on g5, black pawn just played to f5. Clocks cropped out. Move list intact down to move 45.

The reply arrived at 20:18, four minutes later, from an account that answers everything. "42.gxf6 e.p. and nothing else. 42...Kxf6 43.Rd1, equal. Decline the capture and 42...Kg7 43.fxg7 Kxg7 44.Rd7+ is -1.94, depth 24, version and settings noted." The version and settings were noted. What was not noted is that the position had been reached, lost, and abandoned inside eleven seconds, which is roughly the interval between the word "resign" and the opening of a fresh board.

Tessa Fenn, who shares the room where the game was played, timed the gap herself. "Eleven seconds is not review time," she said. "Eleven seconds is how long it takes to decide you are not going to think about it. Then the sentence came through the wall: 'there's only one move here.' I assumed he was talking about the next game."

Within the hour, a second reply quoted the move list against him: game over on move 45, same account, three-day-old history. The poster answered that the puzzle is the position, not the game. "I said only one move keeps it equal. I didn't say I played it."

Inez Gable, filing for the standards board, ruled the post admissible in a note that has already been quoted back to her twice. "A position is admissible as a puzzle if the answer is unique," she wrote. "Provenance is a matter for the archive." She added that the board has never required a poster to disclose whether a submitted position was reached, lost, or invented over a board, and that requiring it would "destroy the hobby's oldest tradition, which is telling people the answer is obvious."

Field correction, logged 21:02: the claim that only one move holds survives contact with the engine. The claim that he found it in time also survives. The claim that he posted a puzzle is retired.

By 21:40 the thread had passed sixty replies, and the same account had posted again from the same game, captioned "harder," move 36, White to play. Three people solved it. The first answer arrived in under three minutes, also to two decimals, and noted the version. Somewhere in the middle of the thread, a commenter observed that the pawn Black never got to f6 had been captured en passant, which at least explained where it went.

The rematch, meanwhile, had been in progress since 20:14:03. He had a new file open and a new position after eleven moves. The engine was still running on the old one.