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2020-05-31T04:53:27Z

Created page with "A constraint is a restriction placed on the '''Sudoku''' puzzle. All constraints are derived from the Rule. Sometimes, '''constraint''' is used as an alias for House...."

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A constraint is a restriction placed on the '''Sudoku''' puzzle. All constraints are derived from the [[Rule]].

Sometimes, '''constraint''' is used as an alias for [[House]].

== Constraint Types ==
; Cell Constraints
: Each [[Cell|cell]] must contain a [[Digit|digit]] between '''1''' and '''9'''.

; Unit Constraints
: Each [[Row|row]] must contain one of each digit.
: Each [[Column|column]] must contain one of each digit.
: Each [[Box|box]] must contain one of each digit.

== Background Information ==

Sudoku is a [[constraint satisfaction problem | Constraint Satisfaction Problem]] (CSP). The grid must be completed in such a way that all constraints are satisfied. The size of each house matches the number of available digits. In a standard Sudoku, there are 9 digits and each house therefore contains 9 cells. With 27 houses, there are 243 unit constraints. In addition, there are 81 cell constraints, giving a total of 324 constraints.

Each of these 324 constraints has 9 possible [[Candidate|candidates]].

Constraint - Revision history

Rooted: Created page with "A constraint is a restriction placed on the '''Sudoku''' puzzle. All constraints are derived from the Rule. Sometimes, '''constraint''' is used as an alias for House...."