Sly ArcadeRead the bulb before the tip.
An original lesson from the verified puzzle collection.
The rule
Use ordinary Sudoku units. Digits increase strictly along each thermometer, starting at the round bulb.
Read the constraint
Digits strictly increase from the filled round bulb along the drawn path. Bends do not reset the order. On a four-cell thermometer the bulb is at most 6 and the tip is at least 4.
Connect the candidates
A placed 5 at the second cell of a four-cell path forces later cells above 5 and 6. Compare those bounds with the ordinary units; a removed candidate can make another cell a single.
Make a justified move
Two paths can influence the same row or box without touching. There is no extra anti-knight rule in this game. The direction and the current candidate sequences are what justify eliminations.
A real puzzle example
Open thermo-sudoku-001, then focus on r1c7. The explanation below is generated from this puzzle’s logical proof, without looking up its answer.
Reveal the explained next step
- Digits strictly increase from the bulb to the tip. Only increasing candidate sequences survive.
- Digits strictly increase from the bulb to the tip. Only increasing candidate sequences survive.
- Every other digit is excluded by the current units and constraint candidates.
The justified digit is 3.
Practice without a penalty
Use Notes to record options. Undo restores digits and notes together. Hints reveal attention, explanation and conclusion in separate steps. All 200 puzzles are open. A daily selection is a replay from the verified pool, with its own save.
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