John Rahn

Cool tools: Polysemic and non-commutative Nets, subchain decompositions and cross-projecting pre-orders, object-graphs, chain-hom-sets and chain-label-hom-sets, forgetful functors, free categories of a Net, and ghosts

Abstract Expressive tools work primarily on the problem of the clarity and style of expression of models in some underlying theory. There is a structure among mathematics, a theory of the world (e.g. music), expressive constructs with their own structure, the applied theory, and models of some real entity. Lewins transformational networks are expressive tools of great currency in music theory. We generalize Lewin-nets to Nets, which, unlike Lewin-nets proper, are both polysemic and non-commutative. We show how all kinds of Nets work on both simple and complex data objects, and how this is all useful in expressing musical analysis. We then show some ways that Nets connect with category theory and topology. We construct chain-hom-sets and chain-label-hom-sets in Nets that form free categories on object-graphs and transformation-graphs, and show how each chain-hom-set of paths consists of all possible musical compositions between an initial and final musical object in a chain within a particular Net. We note how the temporal partial order of any piece of music plays against the structural pre-order of its Net representation, and how the various partial and pre-orders cross-project against one another. There is a family of forgetful functors that relate the various categories Net, Object-graph, Transformation-graph, and Grph. We show how to get from both proper Lewin-nets and from Nets to an underlying pre-order such that the labelling arrows of the Net can then be construed as a pre-sheaf over the pre-order. We point out the interesting ghosts that survive all the forgetful functors, that is, the particular characterizing structures of each digraph (or transformation-graph or object graph) which then, reading upwards, constrain the possibilities for labelling its arrows and nodes in any superior entity (such as a Net) built on it.

Dual-modal optical projection tomography microscopy for cancer diagnosis

A dual-modal optical projection tomography microscope (OPTM) is presented, which produces three-dimensional images of single cells with isometric high resolution both in fluorescence and absorption mode. Depth of field of a high numerical aperture objective is extended by scanning the focal plane through the sample in order to enable reconstruction by back-projection method. Cells are fixed, stained, and mixed with optical gel and injected into the capillary for imaging. Combining absorption and fluorescence mode allows us to image different aspects of the disease process. Images of cells stained with both hematoxylin and fluorescence probes are shown. Registrations between two modes are discussed.

Approaching Musical Actions

So, an improvisation has been going on for some time, but its impetus is dying out, at first in a good way, all getting more quiet in a nice contrast to what has gone before, but soon, in fact now, we need a new idea, of course (inescapably) related to what we have been playing already, but one that will have a fresh effect and that can carry us into a fertile territory that will in some way complement what has gone before. I gather up into my mind and intuition some threads that have been woven into everything else so far, and form a tentative image of some new pattern to weave, and I act. The act is the public manifestation of my inner representation of my projection of the music we have played onto the screen of the future. The other musicians respond to this new musical context with their own representations, projections and actions, in a spreading web of new musical relations, represented individually and to some extent variously in each musician, and manifested publicly in our shared acoustic space, which serves as our blackboard — the space in which we communicate to each other.

The Lisp Kernel: A Portable Software Environment for Composition

hind the Lisp Kernel software, its design specifications, and the goals it attempts to serve. Next I will describe the current state of the system, including its basic data structures and categories of procedures, and what the system is capable of doing now. Then I will discuss some of the ways in which various people are now using the Lisp Kernel and some ideas for future development connected to it, including applications of artificial intelligence. Finally, there will be a brief review of other software systems whose ideas are related to those behind Lisp Kernel and some remarks on the desirability of writing software that can talk to other software.

How Do You Du (By Milton Babbitt)

The next ten sounds present six attacks, four pitches, and four pc, in a total timespan of J, a duration 4/3 of the previously described ensemble duration, but equal in duration to the previous timespan if the initial eighth-rest is included, perhaps retrodictively by an already suggested principle of repetition of equal durations ( . . i ). Since the four pitches (pc) of this second timespan contain only three pitches (pc) not previously presented, and for

ICMC88: Crossroads at Cologne

HE 1988 INTERNATIONAL Computer Music Conference was held September 19-25th at Cologne in the Federal Republic of Germany, under the direction of Clarence Barlow of GIMIK (music) and Cristoph Lischka of the Gesellschaft ftir Mathematik und Datenverarbeitung (science). The opening event Monday night set the tone. Those of us who found our way to the tower of the West German Radio entered through a uterus-like passage to a womb-like circular chamber at ground floor, where we were asked to exchange money for tickets. After liquid refreshment, we were allowed to transfer (swimming upstream) in elevator-sized blocks to the upper saucer overlooking the city. As we walked from the elevator around the circumference of the saucer to the banquet room, it occurred to some of us that the event was very like a piece by Clarence Barlow.