Bistromathics are a relatively newly discovered form of technology, science, and transport. As time is relative to factors, memories, ways organisms remember things, and time travel, it is impossible to say whether Bistromathics are newly discovered, appallingly ancient, or non-existant at the time. Bistromathics are the study and technology of restaurants, as numbers in restaurants are unlike those anywhere else in the universe, due to the large amount of non-absolute numbers in the restaurant setting.
A notable use of Bistromathics is the Bistromathic Drive, a power source and engine much like the Heart of Gold, except resting on the science of Bistromathics instead of improbability drive. There is, inside the ship of the Bistromathic I, what appears to be a small Italian bistro. Everything in the bistro is mechanical, including waiters, customers, and tables, all of which act together in a complicated routine to power the ship. Things such as stirring one's coffee, arguing with the robotic waiter, returning your steak, insisting for a better cooked steak, and arguing about the noise from the robotic party across from you park, power, create, and move the Bistromathic I, in a mind-numbingly complex work of science and manipulating the nature of the universe.
There is below a full history on the workings of Bistromathics extracted from the Guide, although it is notable that this volume, with its questionable sources, should not be trusted.
Quote from the Guide:
"The Bistromathic Drive is a wonderful new method of crossing vast interstellar distances without all the dangerous mucking about with Improbability Factors. Bistromathics itself is simply a revolutionary new way of understanding the behaviour of numbers. Just as Einstein observed that time was not an absolute but depended on the observer's movement in space, and that space was not an absolute, but depended on the observer's movement in time, it is now realised that numbers are not absolute, but depended on the observer's movement in restaurants.
The first non-absolute number is the number of people for whom the table is reserved. This will vary during the course of the first three telephone calls to the restaurant, and then bear no apparent relation to the number of people who actually turn up, or to the number of people who subsequently join them after the show/match/party/gig, or to the number of people who leave when they see who else has turned up. The second non-absolute number is the given time of arrival, which is now known to be one of those most bizarre of the mathematical concepts, a recipriversexcluson, a number whose existence can only be defined as being anything, other than itself. In other words, the given time of arrival is the one moment of time at which it is impossible that any member of the party will arrive.
Recipriversexclusons now play a vital part in many branches of math, including statistics and accountancy and also form the basic equations used to engineer the Somebody Else's Problem field. The third and most mysterious piece of non-absoluteness of all lies in the relationship between the number of items on the check, the cost of each item, the number of people at the table and what they are each prepared to pay for. (The number of people who actually brought any money is only a sub-phenomenon in this field.) The baffling discrepancies that used to occur at this point remained uninvestigated for centuries simply because no one took them seriously. They were at the time put down to such things as politeness, rudeness, meanness, flashiness, tiredness, emotionality or the lateness of the hour, and completely forgotten about on the following morning. They were never tested under laboratory conditions, of course, because they never occurred in laboratories - not in reputable laboratories at least.
And so it was only with the advent of pocket computers that the startling truth became finally apparent, and it was this: Numbers written on restaurant checks within the confines of restaurants do not follow the same mathematical laws as numbers written on any other pieces of paper in any other parts of the Universe. This single statement took the scientific world by storm. It completely revolutionised it. So many mathematical conferences got held in such good restaurants that many of the finest minds of a generation died of obesity and heart failure and the science of math was put back by years. Slowly, however, the implications of the idea began to be understood. To begin with it had been too stark, too crazy, too much like what the man in the street would have said "Oh, yes, I could have told you that." Then some phrases like "Interactive Subjectivity Frameworks" were invented, and everybody was able to relax and get on with it.
The small groups of monks who had taken up hanging around the major research institutes singing strange chants to the effect that the Universe was only a figment of its own imagination were eventually given a street theatre grant and went away."