Dash Insert drop-down menu. Dash The dash is a punctuation mark that is similar in appearance to and , but differs from these symbols in both length and height. The most common versions of the dash are the en dash (–), equal to half the height of the font; the em dash (—), twice as long as the en dash; and the horizontal bar (―), whose length varies across typefaces. Historically, the names of en dash and em dash were loosely related to the width of a lower-case "n" and upper-case "M", respectively, in commonly used typefaces. Usage varies both within
Littlewood's rule rejected. If a continuous distribution formula_14 is used to model the demand, then formula_15 can be calculated using what is called "Littlewood’s rule": This gives the optimal protection limit, in terms of the division of the marginal revenue of both classes. Alternatively bid prices can be calculated via Littlewood's model is limited to two classes. P. Belobaba developed a model based on this rule called Expected marginal seat revenue, abbreviated as EMSR, which is an formula_17-class model Littlewood's rule The earliest Revenue Management model is known as "Littlewood’s rule", developed by Ken Littlewood while working at British Overseas Airways Corporation.