Single Comment

Derek:
| The moral of the story is that randomization of move selection 
| reduces  the growth in playing strength that normally occurs with 
| time and plies completed.

This is not how it works. For one, you assume that at long TC there would
be fewer moves to chose from, and they would be farther apart in score.
This is not the case. The average distribution of move scores in the root
depends on the position, not on search depth.

And in cases were the scores of the best and second-best move are far
apart, the random component of the score propagating from the end-leaves
to the root is limited to some maximum value, and thus could never cause
the second-best move to be preferred over the best move. The mechanism can
only have any effect on moves that would score nearly equal (within the
range of the maximum addition) in absence of the randomization.

For moves that are close enough in score to have an effect on, the random
contribution in the end-leaves will be filtered by minimax while trickling
down to the root in such a way that it is no longer a homogeneously
distributed random contribution to the root score, but on average
suppresses scores of moves leading to sub-trees where the opponent had a
lot of playable options, and we only few, while on average increasing
scores where we have many options, and the opponent only few. And the
latter are exactly the moves that, in the long term, will lead you to
positions of the highest score.