we didn't say all the "shots" had to be pocketed shots
Why not multiply all the possible places you can hit the cue ball (spins), by all the different elevations times all the possible angles, times all the different speeds? I don't think the pockets even matter in this particular instance....we didn't say all the "shots" had to be pocketed shots......they're just shots of different speed, spin, angle and distance, we'll take it for granted that the balls must stay level with the table.
Why not multiply all the possible places you can hit the cue ball (spins), by all the different elevations times all the possible angles, times all the different speeds? I don't think the pockets even matter in this particular instance....we didn't say all the "shots" had to be pocketed shots......they're just shots of different speed, spin, angle and distance, we'll take it for granted that the balls must stay level with the table.
More or less as sjm did just above, except I hope players don't waste too much of their time with such problems.
You divide each variable, such as length, into a finite number of pieces. You can either do this to taste or base it on something inherent in the problem. For example, sjm above divided lengths into 1mm sections. That's much too coarse for my taste. If the cue ball lands on the object ball 1mm from where you intend, that will cause a 2 degree error in the path of the object ball. 2 degrees is huge. (Degrees are divided first into minutes, by the way, not into seconds).
So, a reasonable length unit might be taken as how accurately the cue ball needs to be placed on an object ball to make that ball in a distant pocket. Well, what fraction of the pocket do you want to allow? If you're banking a ball long off the spot back to your pocket at one pocket, does it make any difference to you if it goes in the middle or side of the pocket? That's the sort of question that must be answered before you can start using a finite division of the variables.
It is easy to construct other example shots where a tiny change in how the cue ball hits the first ball in a combination makes a large change in the result. I remember reading about someone studying the break shot and concluding that it was basically a chaotic situation, where you need to know almost perfectly all the parameters involved in order to predict how the shot will come out. This all leads to the selection of a very small length unit for a finite analysis.
As soon as something hits a cushion you have probably squared the number of shots.