Intermediate clue

If this fails, that one must be false

Also known in the clue library as Conditional (If not … then NOT …).

conditional-false-false

Clue pattern: If A is not B, then C is not D.
What to mark first: Fire the no-mark only after the first pairing is ruled out.
Common mistake: Using the consequence before the board proves the trigger false.
Mini-example: If Mina is not the baker, Theo is not in the red house.
Print-book tip: Keep the clue in two halves: failed pairing, then no-mark.

When and where this clue pays off

Two questions matter more than the pattern itself: does this clue give you everything now, or only later — and does it become a mark on the board, or a note you have to keep separately?

Builds as the board fills in

This waits for an elimination on both ends. The trigger has to be ruled out before the consequence can be too.

Needs a written note

Track it off the board until the trigger is eliminated.

Reading the clue is half the job. These are the methods that turn it into board progress.

Put it to work

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If this fails, that one must be false

When and where this clue pays off

Techniques that use this clue

Put it to work