Note that we can put a metric (distance function) on the collection of event matrices, for example Euclidean distance will do.
But it is by no means obvious how to produce a choice function for the collection of pairs of arbitrary sets of real numbers.
For example, as already mentioned, it is easy to come up with a choice function for the collection of pairs of real numbers (simply choose the smaller element of each pair).
The rise of scientific and industrial research and the establishment of public libraries in the 19th century led to the greatly increased emphasis on the subject approach and the role of systematic cataloging and classification in addition to the accepted function of building the collection and the consequent need for expert knowledge of bibliography, both systematic and analytic.
"This was a function of reviewing the collection to see where we had great strengths," said Glenn D. Lowry, director of the Modern.
The Mass Flow Number, M, corresponding to the optimum flow of working fluid as a function of the solar collection area, is also considered.
If everything is vibration and probability, then perhaps our thoughts and feelings might affect the delicate and complex function of that collection of parts, electricity, and combustion we call a car, not to mention our personal and office electronic devices.
When we inquire into the way ancient authors have used the information provided by Aëtius' Placita, by its progeny, and by its post-Theophrastean predecessors, we often find that the function of these collections of doxai is not much different from the functions of similar overviews in the context of Aristotle's dialectical discussions.
