Billiard table ivory balls from warping. The first use of electric heating was for an 18.2 balkline tournament held in December 1927 between Welker Cochran and Jacob Schaefer, Jr. The New York Times announced it with fanfare: "For the first time in the history of world's championship balkline billiards a heated table will be used..." A pool table, or pocket billiards table, has six – one at each corner of the table () and one at the midpoint of each of the longer sides ( or ). Pool tables come in different sizes, typically referred to as , , , or tables.
Outer billiard Tabachnikov showed that all orbits are unbounded for a certain class of convex polygons in the hyperbolic plane. The authors call such polygons "large". (See the reference for the definition.) Dogru and Otten then extended this work in 2011 by specifying the conditions under which a regular polygonal table in the hyperbolic plane have all orbits unbounded, that is, are large. In ordinary polygonal billiards, the existence of periodic orbits is a major unsolved problem. For instance, it is unknown if every triangular shaped table has a periodic billiard path. More progress has been made for outer billiards, though the