Brian Hayes’s research while affiliated with Sigma Xi, The Scientific Research Honor Society and other places

Probabilistic algorithms, which make random choices at various points in their execution, have long been essential tools in simulation, optimization, cryptography, number theory, and statistics. The idea is to create a probabilistic programming language (PPL). In a language of this kind, random variables and probability distributions are first-class citizens, with the same rights and privileges as other data types. Monte Carlo simulations and other probabilistic models can be written in any programming language that offers access to a pseudorandom number generator. What a PPL offers is an environment where probabilistic concepts can be expressed naturally and concisely, and where procedures for computing with probabilities are built into the infrastructure of the language. Some of the algorithms embedded in PPLs may also be embedded in people.

A full-scale computer simulation of the galaxy must trace the motions of at least 100 billion stars and other objects over several billion years. The challenge is to solve a 100-billion-body problem. Computational astronomers are preparing to simulate the motions of all the stars in a galaxy the size and shape of the Milky Way, tracing the stars' trajectories over a period of several billion years. A Dutch-Japanese collaboration team led by Simon Portegies Zwart of the Leiden Observatory has completed a pilot study of 51 billion stars.

Three communities in the world of computation, computer science, computational science, and software development, are bound together by common interests but set apart by distinctly different aims and agendas. The object of study in computer science is the computing process itself, detached from any particular hardware or software. In computational science, the computer is not an object of study but a scientific instrument, a device for answering questions about the natural world. Software development is all about making things, not answering questions. According to the author, Brian Hayes, computing has been a fragmented field. As the push to teach more people to code grows, an increasing number of people will start acquiring programming skills, but there is no unified approach to programming, so the field is likely to continue to fragment as these new coders take the discipline in their own direction. Hayes notes that several attempts have been made over the years to create uniform, professionalized standards and certifications for programming, but they have usually faltered. He worries that ongoing fragmentation seems unwise and unhealthy.

William Shanks was one of the finest computers of the Victorian era. His specialty was mathematical constants, and his most ambitious project was a record-setting computation of pi. Biographical details about William Shanks are hard to come by. Pencil-and-paper computation was a skill more highly prized in the 19th century than it is today. Towards the close of the year 1850, the Author first formed the design of rectifying the Circle to upwards of 300 places of decimals. He was fully aware, at that time, that the accomplishment of his purpose would add little or nothing to his fame as a Mathematician, though it might as a Computer. The only hidden subtlety is that the numeric variables must be able to accommodate numbers of arbitrary size and precision. Shanks does not reveal much about his computational methods.

The literary scholar needs a quiet room, a reading lamp, a notebook, a receptive mind and algorithms for n-gram analysis, part-of-speech tagging, word-sense disambiguation, and sentence parsing. The idea of applying mathematical and computational tools to literature is hardly new. One was a man of science who made a few brief forays into statistical language studies. The other was a professor of English literature who yearned to import scientific methods into his field. The first half of Analytics is a fairly conventional introduction to rhetoric and poetics, with chapters on meter and rhyme, figures of speech, the emotional force of words a lot of close reading. Then Sherman suddenly goes all quantitative, launching into a discussion of sentence length. Sherman was motivated by broader questions than the authorship puzzles that concerned Mendenhall. While teaching the historical development of English literature, Sherman took note of pervasive changes in sentence structure.

Endowing a computer with human perceptual skills, such as understanding spoken language or recognizing faces, has been on the agenda of computer science since the era of vacuum tubes and punch cards. If the network gives the correct answer for an image, do nothing. If the system makes the wrong choice, there must be at least one neuron in the input layer that responded incorrectly, either accepting a motif it should have rejected, or vice versa. Find all such errant neurons, and instruct them to reverse their classification of the current motif. Such a network recognizes any pattern of vertical stripes, regardless of the stripes' width. It is a wallpaper sensor. Other subsets of the 16 motifs yield networks triggered by horizontal stripes or by diagonals. The ability to detect stripes in various orientations is intriguing in that the primary visual cortex of the mammalian brain is full of stripe-sensitive neurons.

At first, peas served as particles in Ernesto Altshuler’s experiment. A mechanical dispenser would drop the chícharos one by one into the space between two glass plates, forming a tidy two-dimensional approximation of a sand pile. Lattice structure appeared, then vanished, as the pile self-organized and went critical—avalanche! But Havana’s insects soon found the peas in Altshuler’s physics lab. For a physicist working under harsh economic conditions of Cuba in the early 1990s, options were few. Yet Altshuler’s solution came as a byproduct of the crisis: Because of fuel shortages, the country had begun importing Chinese bicycles, and ball bearings were available in abundance. Thus the peas have been replaced by steel beads, but Altshuler and his students still call their machine the chícharotron.