Outcome
You can connect two matching bivalue cells through a valid Strong Link, prove that one wing must contain the elimination digit, and reject false W-Wings with the wrong link or visibility.
Intro copy
Two remote {X,Y} cells are not automatically related.
W-Wing gives them a logical bridge:
a Strong Link on one candidate.
Step 1 — Start with two matching wings
Show:
Wing A {5,9}
Wing B {5,9}Prompt:
Do these form a Naked Pair?
If they do not share a unit:
No.
Prompt:
What would we need to connect them logically?
Reveal:
A Strong Link on 5 or 9.
Step 2 — Add the link
Show a conjugate pair on 9.
One link endpoint sees wing A.
The other sees wing B.
Prompt:
Which candidate is acting as the link digit?
Correct: 9.
Step 3 — Prove both cases
Link endpoint A = 9
Wing A cannot be 9 → wing A = 5.
Link endpoint B = 9
Wing B cannot be 9 → wing B = 5.
Conclusion:
One wing is always 5.
Step 4 — Eliminate from common peers
Show candidate 5 targets:
- sees both wings;
- sees only A;
- sees only B.
Learner removes only the common-peer target.
Feedback:
The Strong Link is on 9, so 5 is the elimination digit.
Step 5 — Guided board
Learner:
- finds repeated bivalue signature;
- chooses one candidate as potential link digit;
- finds conjugate pair;
- matches opposite endpoints to wings;
- proves both cases;
- removes the other candidate.
Step 6 — False Strong Link
Show a proposed W-Wing where the “link digit” has three positions in the source unit.
Prompt:
Valid W-Wing?
No.
Feedback:
The bridge is only Weak. If one endpoint is false, the other is not forced true.
Step 7 — Simpler Pair comparison
Show two {2,8} wings that actually share a box.
Prompt:
Which explanation should you try first?
Correct:
Naked Pair.
This reinforces the simplest-valid-proof rule.
Practice
Include:
- row/column Strong Links;
- box Strong Link;
- invalid Weak-only bridge;
- invalid common-peer target;
- Naked Pair decoy.
Hint ladder
- “Look for matching bivalue cells.”
- “Choose one shared digit.”
- “Can that digit connect the wing regions through a Strong Link?”
- “One link endpoint must be true.”
- “Which wing candidate is therefore guaranteed somewhere?”
- Highlight common-peer eliminations.
Completion
Three valid W-Wings plus three false/simpler-structure classifications.
Next
Unique Rectangles
The next lesson changes logical premise: uniqueness techniques rely on a verified one-solution puzzle.
Reference
Read W-Wing for the full Strong-Link proof and Chain interpretation.