What is the unique rectangle rule in Sudoku?

The unique rectangle strategy focuses on a particular arrangement of candidates that is sometimes referred to as the "deadly pattern." In this pattern, there are four squares in a rectangular formation that each contain the same two candidates, along with other candidates in at least one square.

How does unique rectangle work in Sudoku?

UNIQUE RECTANGLE (TYPE 2) : If two corners of the rectangle in the same Row or Column are "Bi-Value" Cells with the same candidates and if the other two corners of the rectangle are "Three-Value" Cells with the same candidates plus one common candidate, then that common candidate must be the solution in one of the " ...

What is a Type 4 unique rectangle in Sudoku?

A Type 4 Unique Rectangle occurs when one of the digits belonging to the non-unique rectangle forms a conjugate pair in cells that have additional candidates. Thanks to this, we can remove the second digit of the non-unique rectangle from these two cells.

What is unique about a rectangle?

A rectangle is a four-sided polygon in which the opposite sides are parallel and equal to each other. It is one of the types of quadrilaterals in which all four angles are right angles or equal to 90 degrees. The rectangle is a special type of parallelogram with all its angles equal.

What is the ambiguity rule in Sudoku?

During this process the designer must be careful not to remove two numbers that would cause an ambiguity (where those two numbers could be swapped and the puzzle could be completed two different ways, therefore having two solutions). This is what is called the sudoku ambiguity rule.

Unique Rectangles Part 1 / Sudoku Tutorial #20

What is the hidden triple rule in Sudoku?

"Hidden triples" applies when three cells in a row, column, or 3x3 block contain the same three Notes. These three cells also contain other candidates, which may be removed from them.

What is the 45 rule in Sudoku?

The 45 rule is a basic solving-technique in Killer Sudoku. Each house (row, column, nonet) must add to 45 (the sum of the digits 1 through 9).

What is the theorem of rectangle?

Definition and Theorems pertaining to a rectangle: DEFINITION: A rectangle is a parallelogram with four right angles. THEOREM: If a parallelogram is a rectangle, it has congruent diagonals. THEOREM Converse: If a parallelogram has congruent diagonals, it is a rectangle.

What are the 2 unique properties of a rectangle?

All the angles of a rectangle are 90° Opposite sides of a rectangle are equal and Parallel. Diagonals of a rectangle bisect each other.

What are 3 important things about rectangles?

Properties of a Rectangle

It has 2 dimensions, namely, length and width. Every angle of a rectangle measures 90°. Opposite sides are equal and parallel. It has 2 diagonals of equal length.

What is the Sudoku magic square?

The markings on the back of the turtle were in fact a magic square. A magic square is a square grid filled with numbers, in such a way that each row, each column, and the two diagonals add up to the same number.

What is swordfish Sudoku?

A Swordfish is a 3 by 3 nine-cell pattern where a candidate is found on three different rows (or three columns) and they line up in the opposite direction. Eventually we will fix three candidates somewhere in those cells which excludes all other candidates in those units.

What is Sudoku uniqueness controversy?

Uniqueness in Sudoku

The problem is, that uniqueness in published sudokus is not part of the Sudoku rule itself ("any row, column, and block must contain the digits 1 through 9"). This has led to a very heated argument, whether Uniqueness Techniques are valid or not (see Uniqueness Controversy at Sudopedia).

What is the secret to solving Sudoku puzzles?

The most basic strategy to solve a Sudoku puzzle is to first write down, in each empty cell, all possible entries that will not contradict the One Rule with respect to the given cells. If a cell ends up having only one possible entry, it is a "forced" entry that you should fill in.

How do you know if Sudoku has unique solutions?

It turns out that for a Sudoku of rank n, at least n²-1 distinct symbols must be used for the puzzle to have a unique solution.

How many unique solutions are there in Sudoku?

There are 6,670,903,752,021,072,936,960 possible solvable Sudoku grids that yield a unique result (that's 6 sextillion, 670 quintillion, 903 quadrillion, 752 trillion, 21 billion, 72 million, 936 thousand, 960 in case you were wondering). That's way more than the number of stars in the universe.

What are the 4 unique properties?

The four unique properties of water that make it unique are high specific heat, high polarity, adhesion cohesion, and a lower density as a solid.

Is square a unique rectangle?

A square is a special kind of rectangle, it is one where all the sides have the same length. Thus every square is a rectangle because it is a quadrilateral with all four angles right angles. However not every rectangle is a square, to be a square its sides must have the same length.

What are the 4 properties of a rectangle?

What is the perfect rectangle formula?

How to Calculate the Golden Rectangle. To calculate the area of the golden rectangle by hand, simply take the width “a” and multiply by the length “a + b”.

What is the theorem 2 of a rectangle?

Rectangle Theorem #2: A rectangle has congruent diagonals.

What is Sudoku rule of 1?

Rule 1 - Each row must contain the numbers from 1 to 9, without repetitions. The player must focus on filling each row of the grid while ensuring there are no duplicated numbers. The placement order of the digits is irrelevant. Every puzzle, regardless of the difficulty level, begins with allocated numbers on the grid.

What is Sudoku 4 cell rule?

Rules of Quadruple Sudoku

The object of the puzzle is to fill in the whole 9x9 grid with numbers 1 through 9 (one number per cell) so that each row, each column, and each of the nine 3x3 boxes contains all the nine different numbers 1 through 9. The clues are in the form of sets of four special clue-numbers.

What is the last possible number rule in Sudoku?

Last possible number is a simple strategy that is suitable for beginners. It is based on finding the missing number. To find the missing number you should take a look at the numbers that are already exist in the 3x3 block you are interested in, and in the rows and columns connected with it.