[0,1) = (0) [0,0) = () [0,0] = (0) [0,x] = () Probably you'd say x=-1 but if you're using unsigned indices, then you can't distinguish the biggest

[0,1) = (0) [0,0) = () [0,0] = (0) [0,x] = () Probably you'd say x=-1 but if you're using unsigned indices, then you can't distinguish the biggest possible sequence from the empty one (this is true of all schemes, actually, but at least the other don't require negative numbers).