@4604
"the moves in ICCF games are generally SF's moves" ++ No, not at all. You do not know ICCF.
"agreed draws and resignations represent possible blunders"
++ No, ICCF (grand)masters are not forum dwellers.
They resign when lost and agree on a draw when it is a draw. They often play on for months in drawn positions hoping in vain for an error (?) by the opponent.
"accounting for most of the results in your sample." ++ All wins are by resignation, draws are by agreement, by 3-fold repetition, or by claiming a 7-men endgame table base draw.
"These do not occur with a constant probability mass throughout the game but always at the end." ++ 127 of 136 games are error-free. When an error is made in 9 out of 136 games, the side who made the error realises this next move and resigns. That is why the few errors usually are at the end.
"You count a full point blunder as two errors (half point blunders) but why should this correspond with the square of the probability of a half point blunder." ++ That is a reasonable assumption. It does not even matter. ICCF has no blunders (??), only 9 errors (?) in 136 games.
"the full point blunders are clearly not independent."
++ There is only one error (?) per game in ICCF, so independent or not does not matter.
After a full point blunder the chances of another full point blunder before the next half point blunder are greater than after (impossible immediately after).
++ Does not matter for ICCF: only 1 error (?) in 9 out of 136 games.
@4603
"Yes, you can rule out some moves by knowledge".
++ That is also what van den Herik wrote: 'Next to brute-force methods it is often beneficial to incorporate knowledge-based methods in game-solving programs.' 5.2 p. 303
https://www.sciencedirect.com/science/article/pii/S0004370201001527
"And in some cases you will be wrong to do so."
++ No, then it is not knowledge. That is why the good assistants need to be (ICCF) (grand)masters. They can simplify and prune, but only if they are certain they are not wrong.
"That is the nature of imprecise inductive knowledge."
++ No, that is the power of precise knowledge and logic.
The 20 first moves have been ranked. The best moves are 1 e4, 1 d4, 1 c4, 1 Nf3.
If the 4 best moves cannot win, then the 16 worse moves cannot win either.
That allows to collapse 20 * 20 = 400 possibilities to 4, e.g. 1 e4 e5, 1 d4 d5, 1 c4 e5, 1 Nf3 d5
1 e4 e5 2 Ba6 can be discarded at once: loses a piece without any compensation.
1 e4 e5 2 Nf3 Nc6 needs to look at 3 Bb5, 3 Bc4, 3 d4, 3 Nc3.
It is again useless to look at 3 Ba6.
It is useless to look at 3 Na3: cannot be better that 3 Nc3.
It is useless to look at 3 b4: loses a pawn without any compensation
It is useless to look at 3 Nxe5: loses a piece without any compensation.
It is useless to look at 3 Ng5 or 3 Nh4: loses a piece without any compensation.
Do not let 'rigour' stand in the way of progress by ignoring knowledge and logic.
Do not confuse 'rigour' and 'stupidity'