Sudoku Construction (Creating a Sudoku Puzzle)

It is commonly believed that Dell Number Place puzzles are computer-generated; they typically have over 30 givens placed in an apparently random scatter, some of which can even be deduced from other givens. They also have no authoring credits. Nikoli Sudoku are hand-constructed, with the author being credited beside each puzzle; the givens are always found in a symmetrical pattern. Dell Number Place Challenger puzzles also list author credits.

Building a Sudoku with symmetrical givens can be achieved by determining in advance where the givens will be located, and only assigning an actual number to them as needed. Great caution is required in constructing a Sudoku puzzle, as failing to recognize where a number can be logically deduced at any point in construction - regardless of how torturous that logic may be - can result in an unsolvable puzzle when defining a future given contradicts what has already been built.