Jeiqi notation (FEN) is the set of various abbreviator notational systems used to describe the Jeiqi position or moves in a Jeiqi game record.
Names & notations
- Jeiqi piece: a dark/unseen/covered piece
- Reveal move/revelation: a move of a Jeiqi piece. A Jeiqi piece should do the first move as the original piece in which it is located. After the first move it will be revealed / uncovered to show its real material
- Piece names and abbreviations:
King / k Advisor / a Elephant / e Rook / r Cannon / c Horse / h Pawn / p Jeiqi / x
White / w Black / b
It is similar to standard of FEN with some extra information about captures since that information is very important to guess to which piece a dark piece could be revealed.
Standard FEN has 6 fields as below:
1) Piece placement: there are two parts a) piece placement: similar to ches. Use x/X for dark pieces. For example, b) captured pieces: all revealed captured pieces and their numbers, enclosed by brackets . This part appears immediately after the first part, without any space. Pieces with no capture are ignores. Jeiqi pieces are not compulsory since we can calculate them from the board and revealed captures. That can make the FEN string a bit shorter, avoid redundancy and inconsistent data, avoid ugly using 2 digit numbers (jeiqi pieces could be 15 - two digit number). Empty brackets could be omitted too. Pieces can be placed in any order. For being beautiful, it is suggested to list all white pieces first, descending by piece values. For examples,
Example of a capturing record: [C1H2P3r1p3]: white loses 1 Cannon, 2 Horses, 3 Pawns, 1, black loses 1 Rook, 3 Pawns
2) Active colour: similar to chess, w for white, b for black
3) Castling availability: ignore. Use ‘-’ instead
4) En passant: ignore. Use ‘-’ instead
5) Halfmove clock: similar to chess. This is the number of halfmoves since the last capture or pawn advance
6) Fullmove number: similar to chess. The number of the full moves. It starts at 1, and is incremented after Black's move
Examples: Starting position, empty brackets are totally omitted: xxxxkxxxx/9/1x5x1/x1x1x1x1x/9/9/X1X1X1X1X/1X5X1/9/XXXXKXXXX w - - 0 1
Captured Jeiqi pieces (X7) are counted even that is not compulsory. 2e6/4k4/9/2Ha1P2p/2a2P3/9/3p5/4E4/e8/2X1K4[R1C1P1X7r1h1p1d6] w - 3 55
It is similar to Xiangqi about pieces, moves notations and to chess about promotions for revelation.
Basically it is similar to Xiangqimove notations. Columns are named from a to i, rows from 0 to 9. For a move of a Jeiqi piece we notate it as its original piece and use promotion notation for the revelation.
Bellow is a revelation move when a dark piece in original Pawn position i3 pushed to i4 and revealed into an Horse, Rook on i5 moves to d5, dark Horse in b0 moves to c2 and revealed to a Pawn:
Long algebraic notion (LAN):
1) i3i4=h i5d5 2) b0c2=p
Short algebraic notion (SAN): 1) i4=h rc7 2) Hc2=p
Coordinate notation: i3i4h i5d5 b0c2p
The traditional move notation uses column number by side as image. We can use them as Xiangqi with some notes:
- revealing move uses promotional symbol: P1+1=h
- Don’t count dark pieces with revealed pieces of same types for solving ambitious cases. The dark and revealed pieces can be easily distinguished by revealing symbol
- For example, in above board even there are two black Rooks in column 9, their moves can not be ambiguous since r9.1 is definitely by revealed Rook and r9.1=c is definitely by dark one.
Use Jeiqi as the variant name: [Variant “Jeiqi”]
Send from engine
Inform the engine can play Jeiqi variant:
UCI_Variant var jeiqi UCI_Variant var xiangqi var jeiqi
bestmove: as typical but it could not have revelational piece even the moving piece is a dark one. Reason: the engine cannot decides that piece: bestmove a3a4
Send from chess GUI
GUI should adds revelational pieces to dark moves:
Example: position startpos moves e3e4e b9c7c h2h7r i9h9p e4g2