Impossible boards include all previously mentioned strategies and Alternating Inference Chains (for now).
This method is very similar to X-Cycles but extends the creation of links to different candidates.
AIC is a very powerful method and in fact many other previous strategies can be represented as an AIC. When no other strategies work, AIC
usually finds some eliminations. In the future, we would like to add other methods to this section, but for now AIC is good enough to solve
most of our sudoku boards, which would be unsolvable otherwise.