ABSTRACT
The Bavarian chess player Max Bezzel formulated the Eight Queens problem in 1848. The task is to place eight queens on a chess board so that no queen can attack another on the board. As you may know, a queen can attack another piece on the same row, column, or diagonal. And the question is how many solutions there are. It turns out that there are 12 basic solutions. Other solutions can be derived from these by board rotations or mirror reflections for a total of 92 distinct solutions. The efficiency of backtracking comes from abandoning further queen placements after getting stuck. To illustrate the savings, let's look at the solution tree for the Four Queens problem (Figure 3), where the first level nodes give the row positions for the first queen (in column a on the board), the second level positions for the second queen (column b), and so on.
