Thermo-Sudoku by John Bulten

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Thermo-Sudoku by John Bulten


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Theme: Floating 74’s

Author/Opus: This is the 69th puzzle from our contributing puzzlemaster John Bulten.

Rules: Standard Thermo-Sudoku rules.

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 4:00, Master = 5:00, Expert = 10:00

Solution: PDF

Note: Follow this link for more Thermo-Sudoku puzzles. If you are new to this puzzle type, here are our easiest Thermo-Sudoku to get started on. More Thermo-Sudoku puzzles can be found in The Art of Sudoku 2 and Masterpiece Sudoku Mix 2.

  • Roger Strain says:

    Haven’t solved this yet, but the presentation leaves a little ambiguity in my mind. The large section of overlapping thermometers in the center of the puzzle has multiple intersections where you could conceivably traverse from the left either up or down, then follow to the right. I see *extremely* light hints that there might be a diagonal division that would turn them into independent thermometers that always turn down or right, and don’t actually intersect, but it’s too faint to rely on as an intentional design.

    I’m going to attempt the solve as I expect it should be done (increasing values left to right and top to bottom), which I think is the intended approach. Just would be nice to have a little bit of clarity. Looks like an interesting puzzle, so I’m looking forward to giving it a whirl.

  • John J. Bulten says:

    Yes, the intent is that there are 4 central thermometers that share cells but do not visually overlap, but angle at the diagonals. Sorry this was not clear. IMHO a thermo may have intersections but should never have ambiguous intersections.

  • Jackson Bross says:

    I didn’t think the presentation was all that ambiguous (although it’s a novel and clever use of “standard thermometer rules”). When you have a forking/branching path, any branch that ends in a “bulb” has to have low numbers on the bulb end, and any branch that ends “straight” increases until the straight end. This definitely led to a unique solution, so I assume it’s the correct interpretation.

  • Roger Strain says:

    I would generally agree, except that the central portions (C5, R3-5 and R5-7) have neither a bulb nor a straight end; they simply have junctions at both ends, and you could conceivably “go” either direction when tracing the bulbs to flat ends. Don’t get me wrong, it’s a lovely puzzle and once you do make the (very reasonable) assumption that they go that way, it’s a great solve. But I’m a computer guy, and this just felt slightly more ambiguous than I’d like.

  • Juffowup says:

    Great observation Roger. While the middle thermometer heavily implies that those middle sections increase from top to bottom, one could certainly interpret them as increasing in either direction.

    I felt compelled to try and solve this puzzle assuming each of the 3 other interpretations, but alas none of them yielded a correct solution. It would have been exciting had this been the first non-unique solution in GMPuzzles’ long history!

  • skynet says:


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