LEVEL 6
Swordfish
A candidate in three rows is restricted to the same three columns.
How to find it
- Choose one candidate and map it across rows.
- Find three rows covering only three shared columns.
- Remove the candidate from those columns outside the fish.
Candidate-map demonstration
The violet cells mark the pattern and the gold cell marks the resulting placement or elimination. Treat this compact map as orientation; use the verified full puzzle below to practise the actual deduction.
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Common mistakes
- Using cells that do not share the required row, column, box or peer relationship.
- Removing a candidate before confirming every occurrence in the pattern.
- Confusing a possible pattern with a completed logical proof.
VERIFIED PRACTICE
Swordfish training
Loading a mathematically verified puzzle state…
Continue through the fish family
Fish techniques use the same base-line and cover-line idea at different sizes. Follow the sequence to understand exactly what changes before attempting a harder pattern.