17

If these are two real kings, it is not possible. This is because one requirement of checkmate is that the black king is in check which cannot be achieved with any of the white kings, since it would put the white king in check. If you say that white has only one king and a nonstandard chess piece that moves exactly like a king (i.e. this piece can be put ...


16

A King and a Man (or commoner; i.e., a non-royal King) can mate a lone King. The longest distance to mate on a standard 8x8 board is 18 moves. The result quoted above was obtained by H.G. Muller in 2008, see this coment on chessvariants.com: http://www.chessvariants.com/index/listcomments.php?id=28770


8

The Wikipedia page on the Nightrider contains an example from T. R. Dawson, published in the British Chess Magazine in 1925, where a king, knight and nightrider force a mate against a lone king. I guess a similar procedure would work for two nightriders, but you have to be a little more careful to avoid stalemate.


6

Are there any obscure chess variations where this is allowed? There are. One name for the queen+knight hybrid piece is the Amazon. As noted in the Wikipedia entry on the Amazon piece I just linked to, the Amazon appears in the variant sometimes called Turkish Great Chess, a game played on a 10x10 board and featuring besides the Amazon (which is typically ...


5

This piece is widely used in different fairy chess variants. It appears under several names, including Commoner, Guard and Man / Mann. While the table in the Wikipedia article also linked to in @Allure's answer states it's worth about four points, the article itself limits that value to the endgame: In the endgame, where there is usually little danger of ...


5

This is a great question and a fun problem to mull over. Indeed the way it's written on wikipedia one gets the impression that amazon-vs-empress fortresses are trivial and easily attainable for the weaker side, where in fact it's very difficult to even come up with dummy examples where the empress stands any chance of holding (so not surprising not to see a ...


5

I don't know the exact answer for the 10x8 board (used e.g. in Capablanca Chess, where your Janus is called the Archbishop), but I have something that could get you well along toward an exact answer, though with some effort on your part (see further below). On the 8x8 board the max DTM is 17 moves (as you may already know). My conjecture is that the 10x8 ...


4

It's possible to attack all squares. Q - queen N - nightrider Yellow background - attacked only by a queen Red background - attacked only by a nightrider Orange background - attacked by pieces of both types Queens are placed such that 5 longest diagonals in each direction are attacked. This can be done with just 6 queens, so 2 are redundant and result ...


4

I was unable to generate data for exactly what you want, but I managed something with a restriction to 6x6 board. I think it's reasonable to assume that it doesn't make a big difference from 8x8 for this specific case since there are no powerful pieces on the board (with unrestricted movement distance). Available positions are enumerated by starting from a ...


4

I make it 21 moves, but it's quite likely that my home-made Python code (too long and messy to post here!) has mistakes, so please take this with a grain of salt. I get 112 positions which require 21 (white) moves to mate. The first one on the list is the following board, with black to play: (Janus shown as a bishop because I couldn't easily find a ...


4

I haven't heard of that definition being used for a major piece, but it's a neat observation. Such a piece (call it X) should be able to force a checkmate in a K+X vs K situation. Say White's pieces are on d3 and e3, while Black's is on d5: 1) White plays Xd4, and Black's king must retreat. Say ...Kd6 is played. 2) White plays Ke4. Now Xd5 is coming, ...


3

That is an interesting distinction theory. Although this king-like piece could deliver checkmate with the help of the king, I've always considered the difference to be based on the value of the piece. A king-like piece would only be worth the same as the other minor pieces.


3

The king is worth about 4 pawns if its loss didn't lose the game, which means it's neither a minor or a major piece, but something in between. (Major pieces like the rook is worth 5+ pawns; minor pieces are worth 3.)


3

Since my Stockfish fork for fairy chess variants already supports Almost Chess, I added Sort of Almost Chess with both sides having all promotion options (which is what you seem to imply in your question). I ran a search on the given position up to depth 50 with the commands below: setoption name hash value 1024 setoption name multipv value 30 setoption ...


3

You could force a checkmate with two knights and a "king". Because the "king" does not fear being taken, it can move directly in front of the opponent's king, if it is protected by a knight. All it has to do is do this when the opponent's king is on the side of the board and thus cannot retreat - and it is known that two knights and a normal king can force ...


3

It's not a sacrifice, it's a trade after 1. Gxc2 G*b3 and taking the elephant on a3 next. On the other hand, since doubutsu shogi is strongly solved, you can use an engine/tablebase (e.g. https://github.com/fuzxxl/dobutsu) to set up and see the solution anyway. (I haven't done this, though.)


2

According to the Wikipedia variants page, there does not seem to be a variant with a specific name, but there are several variants that use the queen-knight hybrid, which is called an Amazon (appropriate name, and combines rook+bishop+knight movement abilities). So maybe just "Amazon chess" would make sense. The Amazon is used in the following variants (...


2

This is my best attempt thus far, which I believe attacks 236 (all but 20) squares. I used the staircase solution for 8 queens on the central 8x8 region in order to consequentially fully cover the 4 adjacent 8x4 side regions while putting many diagonals through the corner 4x4 regions. Then I placed the nightriders so as to not obstruct any of the queens' ...


2

See my book Fairy chess endings on an n x n chessboard (2017), p. 345 and 414. The ending of king + two nightriders against bare king on board 8x8 is won for the stronger side and the longest win has 22 moves. Also the ending king + knight + nightrider against king is a general win, see page 395.


1

This is the best arrangement that I've been able to find by hand. It covers 248 squares at least once; missing the 8 squares which are the 2 knight moves outwards from each of the center 4 squares. If I've counted right, I believe it covers 148 of those 248 squares at least twice each. I don't expect triple-covered squares to be a tiebreaker for this ...


1

Hi welcome to chess stackexchange. If I had a Knight surely I can trade it for one of these Daddaba guys. So a simpler question is whether KDDD can beat K. If the lone K can reach the corner where he can’t be checked, then he is safe.


1

Non-royal king is a combination of [0,1] leaper (wazir) and [1,1] leaper (fers) and in fairy chess called a erlking. About erlking, see my book Fairy chess endings on an n x n chessboard (2017), page 545. The ending of king + erlking against bare king on board 8x8 is won for the stronger side and the longest win has 18 moves. Also the ending of two erlkings ...


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