Sudoku can be represented by a formula

For the first time in the world, （foldable） Sudoku can be represented by a formula. 5/21

The first structure
Three types of nine palaces
B1 b2 b3
Q2 q3 p1
B3 d1 d2

The second structure
Five categories and nine palaces
B1 b2 b3
B4 q3 p1
B3 b5 d2