Simple or Simplification

There is a simple way to play perfect chess, write down all the possible games of chess, note if the final position is won, drawn or lost, and then working backwards assume each player choses the best line, you will eventually end up with a list of all the best possible games of chess. This is clearly impractical. A compromise is to grow the list of variations as large as possible, in the time permitted, and then evaluate, with the help of strong engines such as Houdini and Rybka, to try and decide the likely outcome from the final position of each variation. This is a gross simplification, but it captures the essence of the method, and allows us to understand a lot of what may go wrong. This method of growing a tree of possible moves, and then evaluating the resulting positions, in the time permitted, is practical. In each of the following worth-solving puzzles, Black is to play. Hopefully you find the best move or combination of moves or strong move or combination of moves by exploiting ways of the simplification ideas. Improve.