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Simple Color Wrap

When one color contradicts itself inside a unit.

Explanation

Color conjugate pairs for one candidate. If two candidates with the same color see each other, that color would place the digit twice in a row, column, or box, so every candidate with that color can be removed.

Simple Color Wrap example Sudoku board 2 9 8 7 6 1 4 4 7 6 5 3 2 8 1 3 5 9 7 2 6 7 3 9 4 5 5 4 3 9 8 9 6 1 8 5 4 2 3 6 7 2 1 5 2 3 6 4 9 4 5 1 7
An example board where Simple Color Wrap applies

Practice tip

After building a simple color chain, compare same-colored cells before looking outside the chain.

Example steps

  1. Choose one candidate and connect its strong links.
  2. Alternate two colors through the chain.
  3. If one color appears twice in a unit, remove that color from the chain.

Try this technique on a real puzzle.

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