For all 0 < i < m-1, we have
To prove (d), we note that when the distance, there are two ways that the next distance
can be j. The first way occurs if the dealer's secret card
has face value m-1-j. This occurs with probability
. The second way occurs if the dealer's secret card
has face value m, thereby overshooting the player's closest secret card
by one, and the face value of
is j+1, making
. This second event occurs with probability
. Thus we have shown (d) for all j < m-1. To finish (d), note that the only way
and
is when both face values of
and
are m. This occurs with probability
.
The first row of M is the absorbing state, hence (c). To prove (b) we consult Figures 1 and 2. We see that the crucial difference between
and
is the penultimate card to
, call it star. the shaded boxes contain the only possible occurences of the other
. If we imagine an arc drawn between any two adjacent
, then we have two cases. The first case occurs when the star card remains vacant -- no
occupy star. Then the same number of arcs which occured in the
event now occur in the
event. In the second case, star is occupied by some
, and now the total number of arcs is 1 more than there were in the
event, giving us a probability of
. In summary
, thus proving (b).
Note that when i>j, the dealer's secret card
could have a face value of i-j, allowing
. This event occurs with probability
and cannot happen when
, whence the different structure of the upper triangular portion of M. In fact the same reasoning as in the proof of (b) allows us to subtract this one event from those occuring in
, thus subtracting a probability of
at the end of the process. This proves (a).