In 1878, William Kingdon Clifford joined this exterior algebra to William Rowan Hamilton's quaternions by replacing Grassmann's rule epep = 0 by the rule epep = 1.
En 1878, William Kingdon Clifford uniu a álxebra externa cos cuaternións de William Rowan Hamilton, substituíndo a regra de Grassmann epep = 0 por epep = 1.