<j> * <k> = [*((((0 * 0 ) - (0 * 0 )) - (1 * 0 )) - (0 * 1)),((((0 * 0 ) + (0 * 0 )) + (1 * 1)) - (0 * 0 )),((((0 * 0 ) + (0 * 1)) + (0 * 0 )) - (1 * 0 )),((((0 * 1) + (0 * 0 )) + (0 * 0 )) - (1 * 0 ))*] by Def10
.= [*0 ,1,0 ,0 *] ;
hence <j> * <k> = <i> by Def6', Lmx; :: thesis: verum