41. In this encoding, zero is the empty set : 42. The Longhorns installed the empty set because they have a wealth of talent at wide receiver. 43. Initializing with the empty set is an optimistic initialization : all variables start out as dead. 44. Another omission for convenience is when is an empty set , in which case may not appear. 45. Then, every number maps to a nonempty set and no number maps to the empty set . 46. Either or both of the left and right set of a form may be the empty set . 47. For example, is there an empty set ? 48. This is often paraphrased as " everything is true of the elements of the empty set ." 49. The empty set and the full space are examples of sets that are both open and closed. 50. Abstract theory still requires that the set of faces include the polytope itself and the empty set .
