Logic Masters Deutschland e.V.

Rules:

• Normal sudoku rules apply.
• Ratio: If two digits are joined by a black dot, then one is double the other.
• Between-Line: Digits along a line are strictly between the digits in the circles on the ends of the line.
• Anti-Knight: Identical digits cannot appear in cells a chess knight’s move apart.

Hint (click and drag to see the hidden text):

The break-in requires that you know a certain theorem of anti-knight sudoku and the Phistomephel ring. That theorem is as follows. In anti-knight sudokus at most one digit can be excluded from the Phistomephel ring, and if so, that digit must be in the center of box 5. Notice that two digits can not be in the center of box 5.