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
⟨ 1 1 1 0 0 1 0 ⟩

       a ← 3‿3 ⥊ ↕9

       ∊ a
⟨ 1 1 1 ⟩

𝕨 ∊ 𝕩: Member Of

Is each cell in 𝕨 a major cell of 𝕩?

       ⟨1⟩ ∊ ↕9
⟨ 1 ⟩

       b ← 3‿3 ⥊ ↕9

       ⟨0‿1‿2⟩ ∊ b
┌·   
· 0  
    ┘

       ⟨1‿3 ⥊ 0‿1‿2⟩ ∊ b
┌·   
· 0  
    ┘