/**/     x < 0 /\ -2x + (x-1) = x/2 + 2
 \/ 0 <= x < 1 /\  2x + (x-1) = x/2 + 2
 \/ 1 <= x     /\  2x - (x-1) = x/2 + 2 /**/
<=>      x < 0 /\ -x - 1 = x/2 + 2
 \/ 0 <= x < 1 /\ 3x - 1 = x/2 + 2
 \/ 1 <= x     /\  x + 1 = x/2 + 2 /**/
<=>      x < 0 /\ -3 = 3/2 x
 \/ 0 <= x < 1 /\ 2 1/2 x = 3
 \/ 1 <= x     /\ x/2 = 1 /**/
<=>      x < 0 /\ x = -2
 \/ 0 <= x < 1 /\ x = 1 1/5
 \/ 1 <= x     /\ x = 2 /**/
<=> x = -2 \/ x = 2