At the beginning of this episode, Troi beats Data in a game of chess...wait, what?
Troi beats
Data at chess?

That can't be right. I mean, chess is complex, but you can't tell me that Data cannot figure out every single possible strategy of every conceivable configuration of pieces. Data didn't see the "completely unanticipated response" to his "classic attack" coming?
There are disputes about the number of possible chess games with estimates ranging from as low as 10,000,000,000,000,000,000,000,000,000,000,000,000,000 to as high as 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000
For comparison, the latter number is roughly equal to the first number times the total number of particles existing in this universe. That is to say, it's not possible to simply make up a roster of every chess configuration and select what to do; one must make decisions about likely courses of action worth studying and discard others. Obviously, those selections may be wrong.