From: George Fernandez EROLS COM> Date: 16 apr 1996 Subject: Shogi Rules >"Randal J. Andrews" ix netcom com> >Subject: Checkmate rule >My understanding of checkmate is based on my knowledge of chess. >However, it may be that the shogi checkmate is a little different. >While playing my computer today, a position like this one arose: > > > 9 8 7 6 > > a wK wS bR -- > > b -- -- -- -- > > c bG -- -- -- Black: P > > >Now, since the rules of shogi do not disallow the moves that put the >king in check, is P*9b a legal move? By chess definition, P*9b would >be checkmate and therefore an illegal pawn drop. However, since >S8ax9b is not disallowed, is the pawn drop in this position a legal >move? Normally, Shogi Master will not allow me to drop a pawn and give >checkmate, but in this instance, it does allow the pawn drop. Does >anyone know for sure? Dear shogi players, I'm surprised that the discussion regarding the illegal "drop-pawn mate" shown in the original diagram got as far as it did and the comments made seemed to raise more questions rather than give answers! At first I thought the question would be answered quickly and simply by stating some accepted version of the rules of shogi, as they apply to "illegal moves", but it seems that there is some ambiguity and confusion as where such rules can be found and exactly what they say. The last version of "The rules of shogi" I have was written in 1993 by Mr. K. Horiguchi 6 Dan[supplement to the January 1993 issue of Shogi Sekai]. The 96 page booklet, written in japanese, is the official rule book accepted by the Japanese Shogi Association. In the manuscript Shogi in Europe, written in English in 1993 by Mr. Hiroyuki Iida 5 Dan for the Japanese Shogi Association there is a Chapter[1] on The Rules of Shogi which were written, "Following the rule book...". While the author recognizes "...that he had not enough time to elaborate these definitions" I feel he covers some key points very well and in particular answers the question at hand. The following definitions were given which apply here: Checkmate: A checkmate is a position in which a King is in check and there are no legal moves to leave the check. Illegal moves: (1)A move is illegal to make a double pawn. (2)A move is illegal to make a deadlocked piece. (3)A move is illegal for a player if his King's square is attacked by an opponent piece after the move.[to remain in check, to move into check or to expose the king to check] (4)A move is illegal to make a repetition check move[Mr. Horiguchi wrote in an addendum the following clarification: "... In the event of perpetual check, if one player player does it FOUR TIMES(three times is permitted), he will lose his game". (5)A move is illegal to make a dropping check move by a pawn which leads to a position in checkmate at once(dropped-pawn mate). Legal moves: A legal move for a player is a move to leave the check by moving pieces on the board or by dropping if his king is in check. Otherwise, a legal move by a piece on the board which can go[move] or a drop move, which is not illegal. Remark 1(condition of ending game): 1. The game is finished if the position is in a checkmate; The player to move loses the game. 2. The game is finished if one player makes an illegal move; This player loses the game. 3. The game is finished if one player has no legal moves; This player loses the game[contrary to chess rules, where a stalemate is considered a draw]. 4. The game is finished if one player resigns; This player loses the game. So, now getting back to the original statements and questions. First, the rules of shogi DO disallow the moves which put the king in check[see Illegal moves(3)above]. Second, P*9b IS checkmate[see checkmate definition above] and therefore an illegal "drop-pawn mate" move[see illlegal moves(5),(3) and checkmate definition above] and lastly Sx9b IS disallowed and an illegal move[see illegal moves(3) above]. In an effort to put this issue behind us, and move on, I'm sharing with you a bizzare diagram from the 1993 rules book[page 93, digram #92]. The diagram was used to illustrate four of the five types of illegal moves[all except the perpetual check]. I don't recommend trying to beat your opponent using this particular strategy! If it is black's turn, he loses(!) because he MUST make an illegal move: (1)doubled pawn,[P* at any unoccupied square other than 1a or 1h]; (2)deadlocked piece[P*1a]; (3)moving into check[K-1h] or (5)the "drop-pawn mate"[P*1h]. Now, if it were white's move then HE would lose, because (3)moving into check[K-1h or capturing a defended piece] is the only choice, he is stalemated and therefore loses! 9 8 7 6 5 4 3 2 1 +--------------------------------------------+ White in hand: | b+P| b+P| b+P| b+P| b+P| bG | bG | bS | | a(1) +---------------+ +--------------------------------------------+ | | | bP | b+P| b+P| b+P| b+P| bG | bB | bR | bB | b(2) | | +--------------------------------------------+ +---------------+ | | bP | bP | bP | bP | bP | bN | bS | bN | c(3) White(GOTE): +-------------------------------------------- | | | | | | | bP | bS | bR | d(4) +--------------------------------------------+ Last Move: | | | | | | | bL | bN | bN | e(5) +--------------------------------------------+ ----------- | | | | | | | bL | bG | bS | f(6) +--------------------------------------------+ Black(SENTE): | | | | | | | | bL | wK | g(7) +--------------------------------------------+ Black in hand: | | | | | | | | bP | | h(8) +---------------+ +--------------------------------------------+ |P | | | | | | | | | bL | bK | i(9) | | +--------------------------------------------+ +---------------+