Answer
CHECK STEP BY STEP WORK.
Work Step by Step
This is done in exactly the same manner as was described in the text for a 9 x 9 Sudoku puzzle.
With the variables indexed from 1 to 4, instead of from 1 to 9, and with a similar change for the propositions for the
2 X 2 blocks: /\~=O /\~=O /\!=l v;=l V~=l p(2r + i, 2s + j, n).
