Monkeymore Sudoku

ALS-XZ

المستوى 10 · Brown Belt

المتطلب السابق: Almost Locked Sets

Overview

ALS-XZ is the simplest ALS chain technique. Two Almost Locked Sets share a restricted common candidate (X), allowing elimination of any other common candidate (Z) from cells seeing all Z's in both sets.

How It Works

  1. Find two ALS (groups of N cells with N+1 candidates).
  2. Find a restricted common candidate X (all X's in ALS1 see all X's in ALS2).
  3. Find another common candidate Z that appears in both ALS.
  4. Eliminate Z from cells that see all Z's in both ALS.

Example

Find two Almost Locked Sets (ALS) - each has N cells with N+1 candidates.

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Tips & Patterns

  • The restricted common X can only be true in one ALS.
  • This forces Z to be locked in at least one ALS.
  • Any cell seeing all Z's in both sets can never be Z.