You find a drawing of an interrupted game of tic-tac-toe (noughts and crosses).
You know that each player was an expert, which means that none of them ever puts herself into a potentially losing position and that each always wins if her opponent gives her the opportunity.
There are two Xs and two Os in the diagram, and it is impossible to tell
whose move it is.
Ignoring symmetry, what is the position?
Source: David L. Silverman:
Ady is of course correct. I transcribed my two solutions incorrectly, but only at the very end of the post.
I have repaired the transcription.... I also redid the possible histories of the two solution patterns, and I am still stuck with these two solutions. They may be seen at the bottom of my (revised) first post.
Edited on November 9, 2018, 2:23 pm