0 a game played by two people on a table covered in soft cloth, in which a cue (= a long stick) is used to hit balls against each other and into pockets around the table
1 a game played by two or more people on a table covered in green cloth in which a cue (= long pole) is used to hit a ball against other balls to send them into the holes along the edge of the table
Billiards are semi-focusing if their boundary components consist of pieces of cylinders and possibly some flat components.
In words, cylindric billiards are toric billiards where the scatterers are cylinders.
Uniform estimates on the number of collisions in semidispersing billiards.
We need to recall the first inputs on rational polygonal billiards.
Here we start the study of a wider class of billiards called projective billiards, free from this shortcoming.
Projective billiards include the usual billiards along with the dual, or outer, billiards.
In this section we summarize some basic properties of semi-dispersing billiards.
Estimates like that play an important role in various questions about billiards.