01 / FOUNDATION
X-Wing
Find two rows in which a digit’s candidates are restricted to the same two columns (or reverse rows and columns). Eliminate that digit elsewhere in the corresponding cover columns.
2 base sets · 2 cover sets
THE OFFICIAL COMPANION LEARNING GUIDE
How to solve X-Wing Sudoku
with visual logic.
Master the X-Wing Sudoku technique by identifying aligned candidates and proving eliminations. Explore interactive 9×9 examples, then advance to Swordfish and Jellyfish patterns.
Pattern intelligence / 01
X-WING · DIGIT 5
Four aligned candidates. One logical deduction.
R2 / R5
INTERACTIVE STRATEGY LAB
Interactive X-Wing Sudoku tutorial
Choose a pattern, progress through the explanation, and watch the candidate map reveal which placements are constrained and which candidates can safely be removed. This is a focused teaching visualization, not a complete Sudoku puzzle.
CANDIDATE MAP / 9×9
TRACKING DIGIT 5
Base rows
Cover columns
Pattern candidates
Eliminations
Highlighted digits represent candidates, not placed values. Other candidates and solved cells are intentionally omitted.
LESSON 01 / 03
The X-Wing
Two rows. Two columns. A powerful elimination.
Step 1 · Find your base sets
THE ADVANCED PATTERN FAMILY
X-Wing vs. Swordfish vs. Jellyfish
The same constraint logic scales as the number of base and cover sets grows. Start with the X-Wing, then progress into more complex candidate arrangements.
02 / EXTENSION
Swordfish
Three base rows confine a digit’s candidates to just three cover columns. Candidate positions need not fill every intersection.
3 base sets · 3 cover sets
03 / ADVANCED
Jellyfish
Four base rows restrict the same digit to four cover columns. The technique applies identical elimination reasoning on a larger pattern.
4 base sets · 4 cover sets
HOW TO READ THE BOARD
From possibility to proof.
Advanced Sudoku is not a guessing game. An X-Wing tells you that the target digit must occupy a constrained arrangement—even before you know precisely which corners contain the final values.
- Base sets: the selected rows containing all relevant candidates for that digit.
- Cover sets: the selected columns containing those base-row candidates.
- Eliminations: candidates in those cover columns but outside the base rows.
The objective is not to decide which corner is correct. It is to prove that candidates outside the pattern cannot be correct.
PRACTICAL SOLVING CHECKLIST
A reliable scan routine
Choose one digit from 1–9 and scan for rows with a limited number of candidates. Identify whether their candidate columns form a shared cover set. Confirm that every relevant candidate in each selected base row lies within that cover set. Then look for eliminations in the cover columns outside the selected base rows.
If the row-based scan fails, rotate the logic and try columns as the base sets.
Return to the guided lab →
HELP & FREQUENT QUESTIONS
X-Wing Sudoku frequently asked questions
Does an X-Wing tell me the exact two cells that contain the digit?
No. The technique proves that the digit must occupy one of two opposite-corner pairings. That is enough to eliminate the digit from other cells in the two cover columns (or cover rows for a column-based X-Wing).
Must all intersections contain the target digit?
No. In larger basic-fish patterns, not every base/cover intersection needs a candidate. What matters is that the selected base sets contain their target-digit candidates only within the selected cover sets and that each selected set participates in the pattern.
What if the X-Wing is oriented vertically?
Swap rows and columns. Two base columns and two cover rows yield eliminations elsewhere in the cover rows.
Are these diagrams playable Sudoku puzzles?
No. They are intentionally simplified candidate maps for teaching specific logical deductions. To play full Sudoku puzzles, use the live platform linked below.
Is this guide part of the X-Wing Challenge book?
It is a companion learning resource for The X-Wing Challenge, a 100-puzzle expert Sudoku release in the Sudoku MindWorks Series™.