Rules of Domino

# Presentation

The Domino puzzle is a challenging puzzle requiring a lot of observation and reflexion. First a board is filled with  28 dominos but the outlines distinguising each domino have disappeared. You must figure out the delimitation of each domino based of the following rules.

1. Each domino must be used.
2. No domino can overlap another domino.
3. The board must be entirely covered.

The grid could have different shapes but under

each grid appeared an convenient list to mark the dominos found. This is an example of a grid and the solution .

And this is an example of the puzzle with the list

# Tips

Frst try to find in the board the occurrence of a selected Domino, for example in the grid it is not yet possible to put the domino 0,0 because it could be placed in two locations (look at the blue outlines).

But if we try with the domino 1,1 we notice that it could appear only in one place, the same is also true for the domino 3,3.

Now in the upper left corner (above the 1,1) the sequence of numbers 6 ,2 6 appears, then the 2 in the middle could only be paired with on of the 6. But if you select the 6 at the right (outlined in red).

Then the 6 at the left will be alone and it would be impossible to match this number with another one, so this breaks the rule 3: that the entire board must be covered. So the only choice is to match the first 6 with the 2 and by the same reasonning we match the second 6 with the 3.

So this is the basic strategies to solve this puzzle.