0 a game played by two people on a table covered in green cloth, in which a cue (= a long stick) is used to hit balls against each other and into pockets around the table -- 撞球運動
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.
