A

A Hidden Single becomes the solution for a cell.A

When there are two candidates that can only be in the same two cells in a unit then these two candidate will eventually fill the two cells.

This doesn't determine which candidate goes into each cell but it does mean any other candidates in the two cells can be removed.

In the Hidden Pair example in Figure 1 the blue cells are a Hidden Pair with the candidates 2 and 4 in row 1.

The values 2 and 4 have to be placed in the blue cells in row 1 because neither of these values can be placed in any other cells in row 1. All other candidates can be removed from these two cells.

Also, it may be noticed that the non highlighted cells in row 1 form a Naked Set on the values 1, 3, 5, 6 and 9. It is often the case that the cells left over in a unit when a Hidden Set is found will contain a Naked Set.A

Just like the Hidden Pair, this pattern does not determine which of the three candidates goes into each of the three cells but it does mean that any other candidates in the three cells of the Hidden Triplet can be removed.

In the Hidden Triplet example in Figure 2 the three blue cells in row 3 are the only cells that can contain the values 3, 6 and 9.

The values 3, 6 and 9 have to end up in the three blue cells because they cannot be placed in any other cells in row 3. All other candidates in these cells can be removed.

The example puzzle has multiple Hidden Set instance that can be seen by starting it in the Helper. The Naked Sets Strategy will have to be disabled to see the hidden sets in this example.

18 March 2018

by Mike Bernstein

by Mike Bernstein

RE: Comments and feedback for hiddenCandidates

Great site, thanks for putting all this together!

Great site, thanks for putting all this together!

Sudoku Rules and Techniques

Sudoku Rules

Acknowledgments

I would like to acknowledge these sites referenced for strategy ideas and solving techniques.

SudokuWiki.Org by Andrew Stuart

PaulsPages.co.uk by Paul Stevens

Sudoku Rules

Cross Hatching

Counting

Naked Set

Hidden Set

Claiming

Remote Pairs

X Wing

XY Wing

Simple Coloring

Fishy Things

Unique Rectangle

X Chain

Aligned Pair Exclusion

Forcing Chains

Finned Fishy Things

Almost Locked Sets

Counting

Naked Set

Hidden Set

Claiming

Remote Pairs

X Wing

XY Wing

Simple Coloring

Fishy Things

Unique Rectangle

X Chain

Aligned Pair Exclusion

Forcing Chains

Finned Fishy Things

Almost Locked Sets

Acknowledgments

I would like to acknowledge these sites referenced for strategy ideas and solving techniques.

SudokuWiki.Org by Andrew Stuart

PaulsPages.co.uk by Paul Stevens