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Checkmating Applet

This page allows you to practice your technique for checkmating a bare (orthodox) King with a King plus one other piece. (For checkmating with a King plus two pieces, go here.) Just move a piece of the side you want to play with, and the computer will reply with the best move for the other player.

graphicsDir=/membergraphics/MSelven-chess/ whitePrefix=w blackPrefix=b graphicsType=png squareSize=35 useMarkers=1 enableAI=0 symmetry=none promoZone=0 maxPromote=0 Fairy piece:X:K:marshall:a1 King::K:king:b2,,d4

Generating end-game table; Please wait.

For trying other board sizes (upto 16 x 16):
Files: Ranks:
Type of board:

Rule variations:

Design your own piece

In the pane below you can define moves of a piece by clicking the squares it should be allowed to move to. First click defines a leaper move to the square. A second click would convert this to a slider/rider move that repeats that step/leap. A third click would remove the move again.

To limit the range of a slider you can click the first square along its path that it should not be able to reach. Clicking on the piece takes away all its moves, and thus clears the entire pane. After you are satisfied with the move, you can press the 'Design Ready' button to play with the piece that moves this way.

Majors and minors

A 'major' is defined as a piece that, together with its own royal, can in general force a win against a bare royal of the opponent. Pieces that cannot do that are 'minors'. In orthodox Chess the situation is clear: KQK and KRK are always won when the strong side is on move, so R and Q are definitely majors. On the other hand, KBK and KNK are draws by 'insufficient mating material': no checkmate positions are possible at all, even not with the poorest possible moves of the bare King ('help mates'), so B and N are minors.

With some pieces there can be mate positions that cannot be enforced. With orthodox King the necessary and sufficient condition for existence of a checkmate position is that the piece can capture to two orthogonally adjacent squares. A Wildebeest (NC) can do that, but it cannot force checkmate; there aren't even any mate-in-2 positions. The number of won positions for such pieces is thus extremely small, and although it is non-zero, we count them as minors.

Coincidentally the major/minor division in orthodox Chess correlates perfectly with piece values, but this doesn't have to be the case in general. The lowest-valued major I could conceive on 8x8 is a leaper with only 5 moves (the Deva, fbrFflW, from Maka Dai Dai Shogi), which in a FIDE context probably would not be worth more than 2 Pawns. (Try it here!) And minors can be more valuable than a Queen. (Think of a color-bound universal leaper, which can teleport to any dark square.)

Whether a piece has mating potential of course depends on how the royal moves: in Knightmate (where the royal moves as a Knight) the Rook is a minor. Board size matters too: a non-royal King is a major up to 14x14, but a minor on 15x15. And on a cylinder board the Rook is a minor, as to force checkmate with a Rook requires a corner. The stalemate result also matters: in Xiangqi even a Pawn is a major, because stalemate is a win.

It can also be a bit vague what generally won means. A piece that moves as Rook in one dimension, and as Dababba in the perpendicular one (e.g. vRsD) has mating potential on any size board, except that on even-sized boards there is a fortress draw when the bare King is on the edge that the piece cannot reach. So it depends on whether you can cut off the King from reaching that edge. (Try it!) With the perpendicular move a Dababbarider (vRsDD) you have even better chances to achieve that, and a relatively small fractions of the possible start positions is draw. (But many more than the 0.5% or so that you typically see in a generally won end-game.)

Majors that have a sub-set of the King moves (such as the Shogi generals) can often not survive on their own against a King approaching them from a vulnerable side. They cannot outrun the King, and can eventually be chased up to the edge and captured there, when they cannot find shelter near their own King. This can cause some 5-10% of the possible start positions to be draws. Even with faster pieces, such as the range-2 Rook, there are drawn positions where the R2 is cut off from its King, and 'dynamically trapped' in a corner area by the bare King on the same diagonal. There is then no way to outflank the King; it can always get on the diagonal where the R2 moves to, and will approach and eventually attack it when it doesn't move. Although the piece cannot be captured as long as it keeps moving, this will eventually lead to a draw by repetition. So there exists a continuous spectrum between minor and major.

This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.

By H. G. Muller.

Last revised by H. G. Muller.

Web page created: 2018-12-23. Web page last updated: 2018-12-23