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Simple Color Trap

When one candidate is trapped by two opposite colors.

Explanation

Color conjugate pairs for one candidate through strong links. Since one color must be true, any outside candidate that sees both colors cannot survive.

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

Practice tip

Pick one digit, build the color chain from houses with exactly two candidates, then scan outside the chain for cells seeing both colors.

Example steps

  1. Choose one candidate and connect its strong links.
  2. Alternate two colors through the chain.
  3. Remove that candidate from any outside cell that sees both colors.

Try this technique on a real puzzle.

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