A1: <k> * <k> = [*((((0 * 0) - (0 * 0)) - (0 * 0)) - (1 * 1)),((((0 * 0) + (0 * 0)) + (0 * 1)) - (1 * 0)),((((0 * 0) + (0 * 0)) + (0 * 1)) - (1 * 0)),((((0 * 1) + (1 * 0)) + (0 * 0)) - (0 * 0))*] by Def9
.= [*(- 1),0,0,0*] ;
- 1 = [*(- jj),zz*] by ARYTM_0:def 5;
hence <k> * <k> = - 1 by A1, Lm3; :: thesis: verum