When some months before publication of the first issue of Organised Sound, Iannis Xenakis sent the editors a previously unpublished set of lecture notes for possible inclusion in the journal, it seemed natural to locate the resulting article within the present issue, whose major theme is 'algorithmic composition' (AC). Whilst Xenakis himself does not use this term, it is evident that he has had a major influence on those who do, as evidenced by his citations in most of the other articles in this issue. Not only has Xenakis been an original thinker in this domain, his article as presented here also illuminates many of his compositional practices, indicated as the working-out of probabilistic formulae. The article ranges wildely, with a section on the UPIC system, and we believe it also captures much of the empathetic, intensely enquiring nature of a mind deeply versed in both scientific and artistic modes of humanist thought.

The Editors are delighted to welcome this contribution from a venerable pioneer of algorithmic composition who is also a member of Organised Sound’s Advisory Board. In this article, edited from notes for a series of lectures delivered in Poland, and not previously published, Xenakis tackles first the questions arising from determinacy and indeterminacy, repetition and variation, symmetry and structure, and multidimensional musical space. He later describes his computer drawing interface, UPIC, and ends with a discussion of some of his statistical compositional methods employing a variety of probability distributions. Much of the article is illuminated by insights drawn from a lifetime’s work in the arts and sciences.

There are two distinct types of creativity: the flash out of the blue (inspiration? genius?), and the process of incremental revisions (hard work). Not only are we years away from modelling the former, we do not even begin to understand it. The latter is algorithmic in nature and has been modelled in many systems both musical and non-musical. Algorithmic composition is as old as music composition. It is often considered a cheat, a way out when the composer needs material and/or inspiration. It can also be thought of as a compositional tool that simply makes the composer’s work go faster. This article makes a case for algorithmic composition as such a tool. The ‘hard work’ type of creativity often involves trying many different combinations and choosing one over the others. It seems natural to express this iterative task as a computer algorithm. The implementation issues can be reduced to two components: how to understand one’s own creative process well enough to reproduce it as an algorithm, and how to program a computer to differentiate between ‘good’ and ‘bad’ music. The philosophical issues reduce to the question who or what is responsible for the music produced?

Algorithmic composition and gambling, two activities associated (in the public mind) with the use of chance, are contrasted. Gambling is based on the concepts of winning and losing. Algorithmic composition is not, or should not be. Problems of mappings of information from one medium to another are considered, along with problems of reception for artworks made with these methods. In the end, the quality of attention given to an artwork may be more critical to its reception than any methods used to construct it. Mr. Yasser’s Piano, Tuning the Furniture of Chaos and Pi and the Square Root of Two, three recent algorithmic compositions by the author, are considered in the light of these thoughts.

This paper deals with the role of the composer in algorithmic music. This role departs from traditional models because of the way computers are used in the compositional process, particularly when signal processing techniques are being integrated with sophisticated formal models to generate musical compositions. We shall examine several types of ‘musical formalism’ in order to bring out the active role of the composer in the compositional process.

Pietro Grossi was the first pioneer of computer music in Italy. During his activities from 1961 to the 1980s he devoted much research to algorithmic composition. Grossi’s first experiments in this field are discussed, dealing particularly with three important phases of his work: initiating algorithmic composition at the S 2F M studio in Florence, writing digital programs at the CNUCE Institute in Pisa, and realising a musical algorithm by translating the curve designed by the mathematician Peano into a sonic form.

A course in Design Structures is discussed. In this course students learn a multi-faceted approach to exploring mathematical and iterative ideas using sonification and visualisation techniques for their own compositional explorations. These ideas are discussed in relation to philosophy, history, technology, scientific paradigms, and cultural context. Some resulting student work is demonstrated.

Reaction–diffusion systems were first proposed by mathematician and computing forerunner Alan Turing in 1952. Originally intended as an explanation of plant phyllotaxis (the structure and arrangement of leaves in plants), reaction–diffusion now forms the basis of an area in biology which is as important as DNA research in the field of biological morphogenesis (Kauffman 1993). Reaction–diffusion systems were successfully utilised within the fields of computer animation and computer graphics to generate visually naturalistic patterning and textures such as animal furs (Turk 1991). More recently, reaction–diffusion systems have been applied to methods of half-tone printing, fingerprint enhancement, and have been proposed for use in sound synthesis (Sherstinsky 1994). The recent publication The Algorithmic Beauty of Seashells (Meinhardt 1995) uses various reaction–diffusion equations to explain patterned pigmentation markings on seashells. This article details an example of the application of reaction–diffusion systems to algorithmic composition within the field of computer music. The patterned data produced by reaction–diffusion systems is used to create a naturalistic soundscape in the piece cicada.

Mirror-Rite is a work for ‘meta-trumpet’, computer and live electronics. The composition is neither notated nor stored, but forms itself as a complex of rule-based structures, transformations and processes around the improvisation of a live performer, its source of both energy and material. This article discusses the ways in which these algorithms deal with interactivity and projection in time, and how the handling of these aspects might permit the assembly of algorithmic elements into a complex dynamic whole, sensitive to (and existing solely within) present circumstances, but demonstrating unity between different performances.

Complete Listing for Volume 1

Detailed information for many of the following tracks may be found in the CD listing within each journal issue and within the corresponding articles.