MathDB

There are

n

blocks placed on the unit squares of a

n \times n

chessboard such that there is exactly one block in each row and each column. Find the maximum value

k

, in terms of

n

, such that however the blocks are arranged, we can place

k

rooks on the board without any two of them threatening each other.
(Two rooks are not threatening each other if there is a block lying between them.)

Problem Statement