The equation (L): (x → y) → (x → z) = (y → x) → (y → z) occurs in algebraic logic and in the theory of the quantum Yang-Baxter equation. KL-algebras are based on this equation and generalize, e.g., Hilbert algebras and locales, (onesided) hoops, (pseudo) MV-algebras, and l-group cones. Every KL-algebra admits a universal map into its structure group, a map that generalizes classical double negation. Using this map, a Glivenko type theorem for KL-algebras is obtained. In the special case where X has a smallest element and double negation is an endomorphism δ, it is shown that δ(X) is an MV-algebra which operates on the kernel δ −1 (1), a BCKalgebra satisfying (L). This leads to an embedding of X into a restricted semidirect product, δ(X) b ∝ δ −1 (1). Conversely, it is shown that any (restricted) semidirect product of an MV-algebra with a BCK-algebra satisfying (L) is bounded such that double negation is an endomorphism.