Double Ko Question
The following positions recently came up in one of TakeNGive's games, and he is curious how this DoubleKo would have been affected by the Ing Ko Rules. Could some sensei or sempai please expound?
After the White 240, Black played 241 at a. This was the first capture in this area in several dozen moves. (Previously, at move 195, Black had played the squared stone, capturing a White at b. But the board was very different then, so I'm sure this would not affect the current status of the kos.)
White then played move 242 at b, capturing the other ko (marked with a circle).
Black 251 was a ko threat in a distant part of the board, which White 252 answered. Black 253 took the ko at a, and White 254 took the ko at b.
Which parts (if any) of this sequence are not legal under Ing rules? Would the status have been different if Black had fought the double ko right away, and not tried to run to the edge with 243 etc.? Thanks for any enlightenment. - TakeNGive