computer-go: hascoding under the super-ko rule

[met@xxxxxxxxxxxxxx]

Here is why I find hash coding under the super-ko rule so "difficult":

A)

Last move: # 1-4
+ O + # + # #
O O O O # # +
# # # # # + #
Status: white can NOT save the 2-2 string


B)
Last move: O Pass
+ O + # + # #
O O O O # # +
# # # # # + #
Status: black can capture the 2-2 string


C)
Last move: # 1-3
+ O # # + # #
O O O O # # +
# # # # # + #
Status: white can save the 2-2 string


D)
Last move: O 1-5
+ O + + O # #
O O O O # # +
# # # # # + #
Illegal: # 1-4
Status: black can NOT capture the 2-2 string


In the position C) there is no moves that are illegal according
to the super-ko rule. The hash code will not include any illegal
points but still white is only alive under the fact that black
can not recapture. Therefore if one would like to have a correct
hashing one will need to extend the hash code to include more
information that just the current set of illegal moves.

The hash code for C) must be different if the position is preceded
in the search tree by the position A) or not.

Any suggestions?
How does your program handle this?

Regards,
Mikael Thulin

PS My program suffer from his "bug" at the moment. However the "bug"
   have not yet stopped the program from finding the correct solution
   for any problem. I have verified that the "bug" do occur inside
   the search three. If you know of a problem that will bring this
   "bug" into life please let me know. ID