What is the least number of white knights that can be placed on a standard chessboard so that a black piece cannot be added to an unoccupied square without being under attack?
(In reply to
Better Upper Bound by David Shin)
12, and at this point, I feel reasonably confident this bound should hold:
. . . . . . . .
. . . . . x . .
. x x . x x . .
. . x . . . . .
. . . . . x . .
. . x x . x x .
. . x . . . . .
. . . . . . . .
Even Better
