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mathematics – Lights-out variant on a tetrahedron
You have a tetrahedron whose faces are covered in 4 ร 4 triangular grids. Each triangular cell has a light and a switch that toggles that light and the three edge-adjacent lights. The blue dots indicate lights that are ON. For the configurations below, answer the following questions.
- Can all the lights be turned OFF?
- If not, whatโs the minimal number of lights that remain ON?
