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Multi Color Trap

When two separate color chains trap an outside candidate.

Explanation

Multi Coloring compares two disconnected strong-link color chains for the same candidate. If two colors from different chains see each other, the opposite colors must contain at least one true candidate, so any cell seeing both opposite colors can remove that candidate.

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

Practice tip

Build simple coloring chains first, then compare separate clusters for weak links between their colors.

Example steps

  1. Choose one candidate and build two disconnected color chains.
  2. Find a weak link between one color in each chain.
  3. Remove the candidate from cells that see both opposite colors.

Try this technique on a real puzzle.

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