The left zero of a binary operator ⋄ is a value zℓ such that, for any x, the expressions zℓ and zℓ ⋄ x are equivalent; similarly, the right zero is a value zr such that, for any x, the expressions zr...

The left zero of a binary operator ⋄ is a value zℓ such that, for any x, the expressions zℓ and zℓ ⋄ x are equivalent; similarly, the right zero is a value zr such that, for any x, the expressions zr and x ⋄ zr are equivalent. (Again, some operators may not have left or right zeros.) What are the left and right zeros for ⇒ (if they exist)