Neighborhoods of agents
index = [playerList begin: self];
while ((aPlayer=[index next])) {
[self setNeighborhood: aPlayer atDX: -1 DY: 0];
[self setNeighborhood: aPlayer atDX: 1 DY: 0];
[self setNeighborhood: aPlayer atDX: 0 DY: -1];
[self setNeighborhood: aPlayer atDX: 0 DY: 1];
Each player has a list to hold neighbors
Code here picks out players in “Von Neuman” neighborhood