Interesting chess notation problem

   I believe I have read in some chess books that when two pieces of the same type can move to the same square one can always uniquely identify the move by designating either the rank or the file (in some cases it must be one or the other) of the piece to be moved. I discovered today that this is not true.

In standard chess notation there may arise a situation where one must uniquely identify a piece by BOTH its rank and file. Usually when the move would otherwise be ambiguous the piece may be identified by either rank or file or sometimes it must be rank or must be file. For instance we see the notation Nge7 to distinguish from Nfe7 in some games. Today I figured that it can sometimes be the bizzarre case that one must identify the piece and BOTH rank and file. As far as by reasoning goes, it occurs most easily with queens.

 When one player has, under bizzarre circumstances, three queens. Let's suppose that a player has a queen on g8, a queen on f8 and a queen on g7. On that player's move the player may decide to move any one of the three pieces to f7 on the subsequent move. In addition writing Qgf7 will not uniquely identify the piece to move because it could refer to either queen on the g file. Writing Q8f7 does not distinguish between the two queens on the 8th rank. In the case where the player wishes to move the queen from g8 to f7, one MUST write Qg8f7. Uniquely identifying the exact position of the queen to be moved. It's easier to think about if you draw up the position on a board.

I thought this was interesting and wonder if anyone here had encountered this or pondered this before.

Cheers,

JWILD

PS. It can also occur with knights (using the even more bizzarre case where several pawns get underpromoted to knights). It requires several pawns being promoted to knights and then occupying the squares that would be attacked if the knight were on a central square (let's take e4 for instance). Knights on g5, g3, f6, f2, d2, d6, c3, c5. I believe in this case, ANY knight move to e4 must be identified using both the rank AND file of its initial position.

Now Bishops and rooks. Four bishops placed at b2, b8, h2, h8. Any bishop moving to e5 must be uniquely identified.

Finally, I don't think this can happen with rooks.