A gyrogroup (G, ⊕ ⊕ ) is gyrocommutative if its binary operation obeys the gyrocommutative law: a ⊕ ⊕ b = gyr[ a, b ](b ⊕ ⊕ a). For relativistic velocity addition, this formula showing the role of rotation relating a + b and b + a was published in 1914 by Ludwik Silberstein.