127.0.0.1: Created page with "When solving a Sudoku, it is impossible to remember which candidates are available for each cell. Yet, many solving techniques require that you know which cand..."

2021-10-24T10:13:57Z

Created page with "When solving a Sudoku, it is impossible to remember which candidates are available for each cell. Yet, many solving techniques require that you know which cand..."

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When solving a [[Sudoku]], it is impossible to remember which [[candidate]]s are available for each [[cell]]. Yet, many [[solving technique]]s require that you know which candidates are available.

Placing pencilmarks is one solution to this problem. The remaining candidates are pencilled in small digits in the edges of the cell, or placed as small dots in a 3x3 pattern, each position representing a [[digit]].

Most helper programs offer a tool that maintains pencilmarks automatically.

A '''pencilmark grid''' or '''PM grid''' is a diagram in which all the remaining candidates are shown. Annotations are often used to show which cells are involved in the next solving step.

This is an example of a pencilmark grid:
.------------------.------------------.------------------.
| 19 7 169 | 2 156 3 | 459 8 49 |
| 3 4 5 | 7 9 8 | 1 2 6 |
| 2 169 8 | 16 4 156 | 3579 35 379 |
:------------------+------------------+------------------:
| 4 136 1367 | 5 1367 9 | 8 36 2 |
| 17 5 12367| 8 12367 4 | 367 9 37 |
| 8 369 23679| 36 2367 26 | 34567 3456 1 |
:------------------+------------------+------------------:
| 1579 139 13479| 13469 12356 1256 | 23469 346 8 |
| 159 8 1349 | 13469 12356 1256 | 23469 7 349 |
| 6 2 349 | 349 8 7 | 349 1 5 |
'------------------'------------------'------------------'
== Complementary Pencilmarks ==
Some players use pencilmarks not to represent remaining candidates, but the eliminated candidates. This reduces the need for an eraser, but it requires you to look at the grid from a different perspective.

Pencilmark - Revision history

127.0.0.1: Created page with "When solving a Sudoku, it is impossible to remember which candidates are available for each cell. Yet, many solving techniques require that you know which cand..."