DarkKnight Wins Chinese Dark Chess Tournament

The computer Chinese dark chess tournament was held as part of the 19^th Computer Olympiad, which took place in Leiden, The Netherlands, from June 27^th to July 3^rd, 2016. Five teams participated in the Chinese dark chess tournament. Table 1 lists the participants.

OPEN IN VIEWER

Table 1

The participants

The game of Chinese Dark Chess has evolved from and is played with the pieces and half board of Chinese Chess. The 32 pieces are all face-down and randomly put on the 4×8 board when the game starts. Two players alternately flip, move or capture a piece. The player who first captures all pieces of the opponent wins the game. The game draws when no flipping or capturing occurs within 180 plies, or when the same position occurs three times. More details of the rules of playing Chinese dark chess are described in (Chen et al., 2010; Yen et al., 2015).

The tournament was organized as a round-robin with each program playing all other programs, once as first player and once as second player. Each game was played on a game-playing platform developed by Jr-Chang Chen (Tseng et al., 2013). In each round, each program connected to the platform through a network and played two games against its opponent automatically. When a game started, the platform randomized unrevealed pieces for the game. When a game ended, the platform judged the result of the game, and stored the game record. Throughout, each program had 15 minutes per game for its moves.

For each game, the winner obtained 1 point while the loser obtained 0 and both obtained 0.5 for a draw. The cross table is listed in Table 2. DARKKNIGHT and YAHARI respectively won the gold and the silver medals of the 19^th Computer Olympiad, with 5.5 and 4.5 points respectively. The design and implementation details of DARKKNIGHT and YAHARI are described in (Hsueh et al., 2016) and (Chen et al., 2015) respectively. The next two teams, NEWBIEDARKCHESS and OBSERVER, tied on 3.5 points. After the playoff as in Table 3, NEWBIEDARKCHESS obtained 1.5 points and won the bronze medal.

OPEN IN VIEWER

Table 2

The cross-table

OPEN IN VIEWER

Table 3

The cross-table of the playoff

Selected Games

Here are comments on two games, DARKKNIGHT -v- NEWBIEDARKCHESS as in Fig. 1, and DARKKNIGHT -v- OBSERVER as in Fig. 2. ²

OPEN IN VIEWER

Game 1: DARKKNIGHT -v- NEWBIEDARKCHESS, 1-0.

At move 24, NEWBIEDARKCHESS (Red) revealed a red king on square b3 (probability of 1/19) and thus let DARKKNIGHT (Black) benefit. However, Black was in no hurry to capture the red king and did not do so until Red revealed a red rook on a4. At move 43, Black revealed a black king on c5 and the piece was in danger of being captured by a red pawn. At move 45, Black revealed a red rook on c4, which resolved the crisis and ensured Black’s advantage. However, for the move, there were a 1/6 probability of risks in revealing a red pawn on c4.

Game 2: DARKKNIGHT -v- OBSERVER, 1-0

Before move 53, the difference in the pieces of the two players was very small. However, DARKKNIGHT (Red) was in a bad position because red guards were both unrevealed and red pieces were all in bad places. At move 53, Red revealed a black pawn on d4 and stood worse with almost no chance to win. Afterwards, Red slowly controlled black pieces. At move 84, OBSERVER (Black) made a mistake in revealing a black minister on c1 which was captured by a red minister on b1 immediately. Red seized the opportunity and won the game.

OPEN IN VIEWER

Fig.3

From left to right, Chih-Hung Chen (NEWBIEDARKCHESS), Hung Guei (DARKKNIGHT), Gang-Yu Fan (YAHARI) and H.J. van den Herik.