Night Nite Knight
When a knight tactic alters the position, it seems to happen in the centre. A study of Grandmaster games carried out by Dr Chess show many cases of centralized knights and opens the question as to when the knight is most effective. This has to be answered by examining games with the knight as centerpiece and games where a knight is relegated to the h or a-file. No one has time to do this. The only thing we know is that chess rules allow the knight to be shifted from edge to centre. The test is whether the h or a-file is blocked and the knight is forced to defend the pawn structure.