H. G. Muller wrote on Sat, May 30, 2020 06:42 PM UTC:
The 'unload' modifier
I have been working on an extension of XBetza notation in WinBoard/XBoard: the 'u' modifier. This stands for 'unload', meaning a piece that was captured elsewhere is not removed from play, but reappears in a new location. This to allow pieces that displace others.
After some thinking it occurred to me that it would be best to have a move that has a 'u' modifier to unload the piece on the starting square of that move. This in contrast to other mode specifiers (such as 'm' or 'c'), which specify what the move can do on the destination square. This because the destination square is bound to be occupied by the piece that moves, while the starting square will naturally be emptied. Of course this could be cured by having unloads only on the destination square of a non-final leg of a multi-leg move, but that would just lead to complex representation of simple moves.
So ucR now means a Rook move that captures on the destination, but unloads that captured piece on its starting square. In other word, a move that can swap location with an enemy piece. Similarly, udR would describe a swap with a firendly piece, as in XBetza 'd' stands for "capture friend".
Of course it is possible to use the 'u' in a multi-leg move as well. E.g. afudQ would describe a Queen with a two-leg move. The first leg to an empty square ('m' is the default mode for non-final legs in XBetza), the second leg continuing (as Q) in the same direction ('f'), and doing the friendly swap (udQ). Normally a slider move continuing in the same direction would be pointless. (Well, not entirely; it guarantees the length of the move is at least 2.) But now that the intermediate square (start square of the second leg) is used for unloading, it suddenly becomes relevant where on the path it is. Like with locust captures, the user entering a move would first have to select the intermediate square (which WinBoard indicates by highlighting it in cyan, as with locust victims). After which the target square(s) get marked (in this case only one), and clicking on that would finish the move, where the piece in the destination is bumped to the intermediate square. This is part of the Valkyrie move in Odin's Rune Chess. The full Valkyrie would be QudQafudQ, a normal Queen, a Queen that swaps position with a friend, and a Queen that displaces a friend to a formerly empty square on the path it took.
The 'unload' modifier
I have been working on an extension of XBetza notation in WinBoard/XBoard: the 'u' modifier. This stands for 'unload', meaning a piece that was captured elsewhere is not removed from play, but reappears in a new location. This to allow pieces that displace others.
After some thinking it occurred to me that it would be best to have a move that has a 'u' modifier to unload the piece on the starting square of that move. This in contrast to other mode specifiers (such as 'm' or 'c'), which specify what the move can do on the destination square. This because the destination square is bound to be occupied by the piece that moves, while the starting square will naturally be emptied. Of course this could be cured by having unloads only on the destination square of a non-final leg of a multi-leg move, but that would just lead to complex representation of simple moves.
So ucR now means a Rook move that captures on the destination, but unloads that captured piece on its starting square. In other word, a move that can swap location with an enemy piece. Similarly, udR would describe a swap with a firendly piece, as in XBetza 'd' stands for "capture friend".
Of course it is possible to use the 'u' in a multi-leg move as well. E.g. afudQ would describe a Queen with a two-leg move. The first leg to an empty square ('m' is the default mode for non-final legs in XBetza), the second leg continuing (as Q) in the same direction ('f'), and doing the friendly swap (udQ). Normally a slider move continuing in the same direction would be pointless. (Well, not entirely; it guarantees the length of the move is at least 2.) But now that the intermediate square (start square of the second leg) is used for unloading, it suddenly becomes relevant where on the path it is. Like with locust captures, the user entering a move would first have to select the intermediate square (which WinBoard indicates by highlighting it in cyan, as with locust victims). After which the target square(s) get marked (in this case only one), and clicking on that would finish the move, where the piece in the destination is bumped to the intermediate square. This is part of the Valkyrie move in Odin's Rune Chess. The full Valkyrie would be QudQafudQ, a normal Queen, a Queen that swaps position with a friend, and a Queen that displaces a friend to a formerly empty square on the path it took.