Radix k > 2 by A1, RADIX_4:1;
then Radix k > 1 by XXREAL_0:2;
then (Radix k) + (Radix k) > 1 + 1 by XREAL_1:8;
then A2: (Radix k) - 1 > 1 - (Radix k) by XREAL_1:21;
( k -SD = { w where w is Element of INT : ( w <= (Radix k) - 1 & w >= (- (Radix k)) + 1 ) } & (- (Radix k)) + 1 is Element of INT ) by INT_1:def 2, RADIX_1:def 2;
then (- (Radix k)) + 1 in k -SD by A2;
hence ( ( 1 <= i & i < m implies (- (Radix k)) + 1 is Element of k -SD ) & ( ( not 1 <= i or not i < m ) implies 0 is Element of k -SD ) ) by RADIX_1:14; :: thesis: verum