Sudoku Kyo free sudoku game

Sponsored Links

TOP > Techniques > Hidden Unique Rect's.

Solving Techniques 17
Hidden Unique Rect's.

This is a method of finding hidden unique rectangles.
Below, the [6] in the [156] is X’d out. It can be eliminated as a candidate.

If the upper left blue [156] cell is a [1], then [6] can’t be a candidate for this cell.

A problem arises when the blue [156] is any number other than [1]. The yellow parts become candidates for [1].

Then the lower right blue cell would be a [6], since it is a [16]. In this case, too, if the upper left, blue cell is a [6]…

we eventually arrive at the following diagram.

But lets step back. The four blue cells create a unique rectangle with [16][16], leading to multiple solutions. Therefore, in this case, the blue cell to the upper left is a [5] and not a [6].

Hence, this [6] can be removed as a candidate. Otherwise, we are left with a Sudoku problem which doesn’t work.

Sponsored Links

Hidden Unique Rect's. 2

Below is also a hidden unique rectangle. The X’d out [6] can be removed as a candidate from D3. (The 8s in the same row form a strong link)

If the [68] in the upper left B1 is an [8], then B3 becomes a [6], so the X’d out [6] in D3 can’t be entered there.

If the upper left B1’s [68] is a [6], we have a problem. In this case, there are only two [8]’s in the same row, so even if there are many candidates for D1, it will be an [8]. Furthermore, B3 will also be an [8]. If D3 is a [6], we have a unique triangle where [6] and [8] are interchangeable.

It will hence, not work as a Sudoku problem, and [6] can be removed as a candidate.

reference: sudokuwiki.org

Names of cells in Sudoku

A1A2A3A4A5A6A7A8A9
B1B2B3B4B5B6B7B8B9
C1C2C3C4C5C6C7C8C9
D1D2D3D4D5D6D7D8D9
E1E2E3E4E5E6E7E8E9
F1F2F3F4F5F6F7F8F9
G1G2G3G4G5G6G7G8G9
H1H2H3H4H5H6H7H8H9
I1I2I3I4I5I6I7I8I9

Sponsored Links

Sudoku Kyoto(Number Place)Free Puzzle Game
TOP