Translate the following inference to logic notation: Elisabeth is a police officer or it is cold. If it is overcast, then it is late. If it is late, then William is taking a plane. William is taking a plane if and only if Elisabeth is a police officer. It is overcast or it is not cold. Therefore William is taking a plane.
p or q. r -> s. s -> t. t <-> p. r or ~q. Therefore t.