Practice page for 3-men end-games

[hgm]

I set up a page where people can practice their checkmating skills in 3-men end-games, with various (unorthodox) pieces. It plays by a tablebase, which is generated on the client machine. I had expected JavaScript to be pretty slow at this, so I used a fast algorithm (without using bitboards, as JavaScript doesn't support a 64-bit integer type). But it turns out to generate the EGT almost instantly, which is nice.

The page can be found at http://hgm.nubati.net/rules/EGT.html .

[hgm]

I now equipped the page with an interface to define a custom piece, and also have it calculate an EGT for that.

[Edit]
Toying with this sparked some questions, which could make an interesting contest:

1. What is the weakest piece that in general (i.e. in all positions where there is no tactics that forcibly wins the piece) will be able to checkmate a bare King?
2. What is the piece with such general mating potential that takes the largest number of moves (in the worst case) to force the checkmate?

Surprisingly enough the tentative answers I got for these to questions are completely different pieces; the weakest piece (in terms of average number of moves on an empty board) was not at all the slowest (which took nearly 1.5 times as many moves)!

[Andrew]

Is there a page listing the moves for the different pieces on this page? Or could a small piece of text be added when you select each piece
describing its moves? Thanks, this looks very interesting!

Andrew

[George Tsavdaris]

Is there a page listing the moves for the different pieces on this page? Or could a small piece of text be added when you select each piece
describing its moves? Thanks, this looks very interesting!

Andrew

Just click HERE in that page and then on a piece's name in the list.

[hgm]

Indeed; I used my general 'Interactive Diagram' applet as a GUI on that page, and this goes accompanied by a (normally hidden) legend that gives an overview of the pieces, which again offers the possibility to display the move diagrams of selected pieces in the board. Originally I created this applet with Musketeer Chess in mind (a currently popular variant with communities of 'followers' in a sub-forum on chess.com, as well as a forum of its own). So most piece in the list are Musketeer pieces, and I only added some other commonly known fairies for which checkmating is a challenge as an afterthough.

Now that I added the board for designing a custom piece, I might as well use that to display the move diagram of the currently selected piece, though. This would make things more obvious. (But perhaps a bit annoying when you want to really design a custom piece, as you would have to remove all the moves of the previously tried piece first. But an extra 'Clear' button for that board could solve that. (Or perhaps using a click on the piece itself as a command to clear that board.)