Gérard TAILLE wrote:
Bill, do you have any idea for defining an interesting "bad" move notion or do we have to give up and forget this notion?
Well, to borrow from the chess literature, there are a range of errors from inaccuracies to blunders. I am not exactly sure what an inaccuracy is, but I expect that blunders are very bad and inaccuracies are not bad. Where the threshold to bad is, I don't know. There are tactical, strategical, and psychological aspects to the question.
For instance, if a play is strategically inferior, but the player is ahead, and the play cements the win, I would call it a safety play, not a bad play. Similarly, if the player is behind but anticipates that her play may entice the opponent to make an even worse reply, I would call it a psychological ploy, not a bad play.
I also consider the level of the player. If an amateur dan makes a DDK play, I would normally consider that a bad play, although I could be convinced that it was a desperate attempt. Looking for a place to resign, as they say.
![Wink ;)](./images/smilies/icon_e_wink.gif)
For me, generally speaking, I would consider a play to be bad when, given what is known, it is likely to affect the result of the game.
Gérard TAILLE wrote:
- Click Here To Show Diagram Code
[go]$$W
$$ --------------
$$ | X 1 X O X . .
$$ | . X O O X . .
$$ | X . O X X . .
$$ | . O O X . . .
$$ | . O X X . . .
$$ | . X . . . . .
$$ | . X . . . . .
$$ | X X . . . . .
$$ | . . . . . . .
$$ | . . . , . . .[/go]
Let's try to understand the remaining misunderstanding : is white move
![white 1 :w1:](./images/smilies/w1.gif)
a bad (or whatever you want) move?
Strictly speaking the answer is quite simple : we cannot say white move
![white 1 :w1:](./images/smilies/w1.gif)
is a bad move because a "bad" move has simply never been defined!
Can we go further and try to define what kind of move can be said as "bad"?
Considering the position P above, we can probably try the approach used by CGT by using various environments. Lets imagine a very large ensemble of environment E = {E1, E2, E3 ...}.
Strictly speaking, CGT does not consider environments at all in difference games. Berlekamp introduced the idea of a universal enriched environment, and I based my redefinition of thermography upon it. I have come up with the idea of an ideal environment, but have not written any academic paper making use of it. In terms of an ideal environment or Berlekamp's universal enriched environment, taking the ko is at worst an inaccuracy. If the temperature of the environment is low, that is not an argument for playing in the environment.
Gérard TAILLE wrote:
a strong definition of a bad move may be the following:
If it does not exist an environment in which
![white 1 :w1:](./images/smilies/w1.gif)
is one of the best move, then
![white 1 :w1:](./images/smilies/w1.gif)
is a bad move for this set of environment E.
I think you have to compare the play with the alternatives.
Gérard TAILLE wrote:
Unless E is restricted to a small set of environment (for example you may decide to put in E only the ideal environments for every t values) this defintion seems too strong:
Let's for example take as position P the following position
- Click Here To Show Diagram Code
[go]$$W
$$ --------------
$$ | X a X O O . .
$$ | X O O O O . .
$$ | X b X X O . .
$$ | X O O O O . .
$$ | X X . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . . . . .
$$ | . . . , . . .[/go]
We certainly would like to say that a black move at "a" is bad (seeing the possibility to play at "b") but if E contains all environments made of pure {u|-u} gote points then, by taking the environment {2|-2} a black move at "a" becomes correct! With such defintion it becomes difficult to have a bad move and for me such defintion becomes completly unuseful.
In CGT, with a non-ko environment, a play at
b plainly dominates a play at
a. And, even though nobody has proved it, AFAIK, experience says that it is dominated in ko environments, as well. A play at
a may be correct in some circumstances, but it is still dominated. An amateur SDK who plays it instead of
b is, at best, careless. For an amateur dan player I would say that it is a bad play.
![Smile :)](./images/smilies/icon_e_smile.gif)
By contrast,
- Click Here To Show Diagram Code
[go]$$W
$$ --------------------------
$$ | X a . . . . . . . O O . .
$$ | X O O O O O O O O O O . .
$$ | X b . . . . . . . . O . .
$$ | X O O O O O O O O O O . .
$$ | X X . . . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .[/go]
For an amateur I think I would call a play at
a an inaccuracy.