In each column and region, the digits 0-9 appear exactly once each.

In each row, a set of six different digits appear exactly once each. No two rows share a set of digits.

Digits along a thermometer strictly increase from the bulb to the tip. All thermometers are straight lines.

If a pair of adjacent cells contains a flame, the two digits must be in a ratio of 1 or 2, but one of the digits may be 1 off from that.