Experimental thoughts
There seems to be the following levels of abstraction: Level 1 the purpose of existence What a piece wants regardless the position Attack invasion clear the path to promotion attack a target Defense prevent invasion prevent promotion defend a target What a pawn wants: to promote to keep invaders out give room to its own pieces Summary A piece wants to invade, a pawn wants to promote. No matter the position. Level 2 Invasion A specific position poses limits and restrictions to the pieces. Not everything that they want is possible. An invasion square: on the other side of the board cannot be defended by a pawn anytime soon is in contact with a target or focal point The concepts that revolve around invasion are about creating an invasion point and getting your pieces there Level 3 Defending an invasion square Pawns are the best defenders of invasion squares. Invasion squares that are not covered by pawns must be covered by pieces. The usual concepts involving annihilation of the defender ...