Two, according to the different scope of action, the elimination scheme can be divided into the following three types:
1, the only space that can be filled in a number is called hidden single in box in the "palace" unit, also known as palace exclusion method.
2. The only space that a number can fill is called the hidden single line in the "row" cell, which is also called the row exclusion method.
3. The only space that a number can fill is called the hidden single column in the "row" cell, also known as the row exclusion method.
4. Unique remainder method: using a lattice to find a unique fillable number is called remainder method, and using a lattice to find a unique fillable number is called naked list.
5. The remainder method is a method to delete numbers that have already appeared in peer groups, and each peer group has 20 peer groups.
Extended data:
evolutionary process
On the river map, black spots and white spots arranged in several arrays contain infinite mysteries; The pattern on Luoshu just corresponds to nine numbers from 1 to 9, and the sum of three numbers on vertical, horizontal, oblique and three lines is equal to15;
At that time, people did not know that this was the third-order magic square in modern mathematics. They call this mysterious number arrangement Nine palace map. Scholars at home and abroad have conducted long-term exploration and research on this issue, believing that it is the crystallization of the spiritual thinking of Chinese ancestors and the first milestone of ancient civilization in China.