View this file with results and syntax highlighting here.
Element Of (∊)
∊ 𝕩: Mark Firsts
Mark the first occurrence of each major cell in 𝕩 with a 1, and all other occurrences with a 0.
∊ 4‿5‿6‿6‿4‿7‿5
a ← 3‿3 ⥊ ↕9
∊ a
𝕨 ∊ 𝕩: Member Of
Is each cell in 𝕨 a major cell of 𝕩?
⟨1⟩ ∊ ↕9
b ← 3‿3 ⥊ ↕9
⟨0‿1‿2⟩ ∊ b
⟨1‿3 ⥊ 0‿1‿2⟩ ∊ b