InterleaveString←{
⍝ Can strings ⍵ be interleaved to form string ⍺?
     MM←{((≢⍺)⍴⍋⍋⍺⍳⍺⍪⍵)∊(≢⍵)⍴⍋⍋⍺⍳⍵⍪⍺}   ⍝ Multiset membership
     (∧/⍺ MM∊⍵):⍵(∧/≡⍥,¨)(⍺⌿⍨⊢)¨⍺∘MM¨⍵
     0
 }