# Knights of the Square Sudoku Table

Puzzling Asked on January 4, 2022

 8  .  . | .  .  . | .  .  6
.  .  4 | .  .  . | .  .  .
.  .  . | .  .  . | 9  1  .
---------+---------+--------
.  .  . | .  2  . | .  .  .
.  .  9 | 3  .  . | .  .  .
.  .  . | .  .  . | .  .  .
---------+---------+--------
.  .  . | 9  .  7 | .  .  .
9  .  . | 6  3  . | 4  .  .
.  .  . | .  .  . | 1  .  .

• Normal sudoku rules apply.
• Long diagonals contain only unique values.
• If A is a box-center, and A and B are a knight’s move apart, then A and B ought to be different.

A knight’s move constitutes going up/down by two followed by going left/right by one, or going up/down by one followed by going left/right by two:

. . B . B . .
. B . . . B .
. . . A . . .
. B . . . B .
. . B . B . .


(1) the 9s in columns 3 and 4 contradict the knight's-move restriction.

(2) a 9 cannot be placed in the middle 3x3.

• column 4 has already a 9 in row 7.

• the two spaces in column 5 are both restricted by the 9 in column 3 (same row and knight's move).

• r4c6 is in a main diagonal that already contains a 9 in column 7.

• r5c6 is within a row with a 9 in column 3.

• r6c6 is within knight's move from 9 in c4

there must be an error in the initial values.

Answered by Bobby Ramos on January 4, 2022

A very tough Sudoku, but I think I got it:

Answered by Jens on January 4, 2022