Platon Sudoku · Sudoku Study
Chain endpoints · Core Concepts
The outer candidates are endpoints. In an alternating chain beginning and ending with strong links, at least one endpoint must be true.
This course is adapted from Platon Sudoku App. Read the complete example here, then continue learning and practising in the app.
View on Google PlayDefinition
The outer candidates are endpoints. In an alternating chain beginning and ending with strong links, at least one endpoint must be true.
How to find it
Check the full link order, then identify the candidates outside the first and last links.
Common mistake
Endpoint visibility or a chain-like shape does not replace the link proof.
Short chain
Teaching board · local candidate diagram
Observe candidates
The outer candidates are endpoints. In an alternating chain beginning and ending with strong links, at least one endpoint must be true.
Verify the condition
Check the full link order, then identify the candidates outside the first and last links.
Draw the conclusion
The outer candidates are endpoints; in this chain at least one must be true.
Long chain
Teaching board · local candidate diagram
Observe candidates
The outer candidates are endpoints. In an alternating chain beginning and ending with strong links, at least one endpoint must be true.
Verify the condition
Check the full link order, then identify the candidates outside the first and last links.
Draw the conclusion
The outer candidates are endpoints; in this chain at least one must be true.
Recognition practice
Teaching board · local candidate diagram
Recognition practice 1
Must at least one highlighted endpoint be true?
Draw the conclusion
Yes
Recognition practice 2
Must at least one highlighted endpoint be true?
Draw the conclusion
No
Recognition practice 3
Must at least one highlighted endpoint be true?
Draw the conclusion
Yes
Recognition practice 4
Must at least one highlighted endpoint be true?
Draw the conclusion
No
Recognition practice 5
Must at least one highlighted endpoint be true?
Draw the conclusion
Yes
Recognition practice 6
Must at least one highlighted endpoint be true?
Draw the conclusion
No
Recognition practice 7
Must at least one highlighted endpoint be true?
Draw the conclusion
Yes
Recognition practice 8
Must at least one highlighted endpoint be true?
Draw the conclusion
No
Recognition practice 9
Must at least one highlighted endpoint be true?
Draw the conclusion
Yes
Recognition practice 10
Must at least one highlighted endpoint be true?
Draw the conclusion
No
Recognition practice 11
Must at least one highlighted endpoint be true?
Draw the conclusion
Yes
Recognition practice 12
Must at least one highlighted endpoint be true?
Draw the conclusion
No
Practice
This course is adapted from Platon Sudoku App. Read the complete example here, then continue learning and practising in the app.
View on Google Play