Logic Masters Deutschland e.V.

The Border Parity Act by Patrick Junke

Rules:

Place the digits 1-9 in every row, column, and 3x3 box.

A black dot between two digits indicates one is double the other.

A red dot between two digits indicates they sum to twelve.

The grid is cyclic, meaning that column 9 is considered adjacent to column 1, and row 9 is considered adjacent to row 1. I will refer to this rule as "adjacent+" from now on.

Two adjacent+ digits separated by a 3x3 box border have the same parity.

An X between two adjacent+ digits indicates they sum to 10.
ALL X's ARE GIVEN. That makes it the only negative rule in this puzzle.

Here is a link to a SudokuPad version of the grid.