Jun Maekawa Origami ((full)) Here

Before Maekawa’s formal analysis, origami designers relied on intuition and trial-and-error. Maekawa’s most significant theoretical contribution is now known as the , a necessary condition for a flat-foldable vertex.

Consider a single vertex where multiple creases intersect. For the paper to lie flat without self-intersecting, the sum of alternating angles must equal 180 degrees. By analyzing the angular order around the vertex, Maekawa proved that the total number of creases n must be even, and the parity constraint (M – V = ±2) must hold. jun maekawa origami