geometry - Discrete Peaceful Encampments: 9 queens on a chessboard

Here's a discrete variation of yesterday's puzzle Peaceful Encampments.

You have 8 white queens and 8 black queens. Place all these pieces onto a normal 8x8 chessboard in such a way that no white queen threatens a black queen (nor vice versa).

Or, phrasing the puzzle in a way parallel to Black and white queens on an 8x8 chessboard — changing only one word from that puzzle — I would say:

What is the largest number of queens that can be placed on a regular 8×8 chessboard, if the following rules are met:

1. A queen can be either black or white, and there can be unequal numbers of each type [but if so, we count the smaller population].


2. A queen must not be threatened by other queens of a different color.


3. Queens threaten all squares in the same row, column, or diagonal (as in chess). Also, threats are blocked by other queens [not that this matters].

Can you find a way to place more than 8 queens of each color "peacefully" on an 8x8 chessboard?

Answer

Can I claim Nine-and-a-half? :-)

You can replace either bishop with a tenth queen, but then the other bishop's square must remain empty.