Gérard TAILLE wrote:
Dear Thomas,
This new thread is very interesting ideed. We will see that a great variety of loops may exist and, as a consequence, we have a lack of word: the word "loop" may quite restricted or quite large, the words "cycle" and "isomorphic repetitions" may also be quite unclear.
So let's try to discuss.
Let's take first your definition of a loop. The wording you propose is the following:
A loop of moves, once started, has no end.This wording seems not that clear.
First of all you use the word "move" but a "move" may be either a "play" or a "pass".
=> it is not quite clear if your definition exclude a sequence of three successive passes in the loop.
OC I understand that "has no end" means probably "no three successive passes" but it could not be clear for all readers.
- Click Here To Show Diagram Code
[go]$$W 
pass
$$ +---------------+
$$ | . X X O . O X |
$$ | X 1 3 2 O O X |
$$ | X X X O O X X |
$$ | O O O X X X . |
$$ | . . O . . X . |
$$ | O O O . . X . |
$$ | . . O . . X . |
$$ +---------------+[/go]
Secondly the sequence [
pass]* repeated ad infinitum is a "loop" according strictly to your definition (no end). You prefer saying that it is not a loop but an "isomorphic repetition". Fine but that means that the wording
A loop of moves, once started, has no end.is not quite clear.
As fas as I am concerned I do not have really a problem with the wording "loop" also in this case.
BTW do you suggest a defintion of a "loop" in normal play (taking into account the prisoners?) and another defintion of a loop in confirmation phase?
Thirdly, taking a basic ko and the basic corresponding ko ban, is the sequence
[
capture ko,
pass,
pass,
capture ko,
pass,
pass]* ad infinitum a loop?
Dear Gérard,
It is a bit early, isn't it?
Honte has just finished exploring District #2.
By the way, it seems that someone missed starting the numbering with #1. 
Nevertheless, thanks to Honte's good nose, we were able to take the basic-ko rule back home with us.
Let me answer your questions for the time being...
#################################
Technical term "loop"We will see in the further course of the journey to what extent another term (e.g. "circle", "ring"?) would be more appropriate.
Technical term "move"Currently, "move" has the usual meaning either to occupy an empty intersection of the board ("GENUINE move") or to waive this right (i.e. "pass").
Three successive "pass"There is no way that only three successive "pass" will ever be seen in District #2.
In general, three successive "pass" are nonsens, if they are embedded by two genuine moves. This is because (1 or 2) + 2n "pass" have the same effect as (1 or 2) "pass".
Currently, three successive "pass" can only be the appetiser for consuming many, many more.
We will see in the further course of the journey to what extent a specific "pass for ending the status confirmation" would be needed.
In principle, I am no friend of using the same technical term for two different pairs of shoes. This would run into similar problems as we have already encountered with "DAME".
Sending two, returning oneDuring actual play, any repeated sequence that affects the difference of prisoners in only one direction will not last forever. Therefore, is cannot be a "loop". If you ever wanted to maintain "loop", this would be a "temporary loop" in my understanding.
On the surface it looks like you are going to end up in the same place over and over again, but in fact that is not the case. Just because "position" during actual play is a compound of "board position" and "difference of prisoners".
During status confirmation, captured stones do not matter. Therefore, such a repeated sequence is a "loop".
capture ko, pass, pass, capture ko, pass, passWe will have to wait and see if Honte finds something like this in District #6.
_________________
The really most difficult Go problem ever:
https://igohatsuyoron120.de/index.htmIgo Hatsuyōron #120 (really solved by KataGo)
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pass for end of status confirmation
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stone ?
stones ?