Instrumentation: mixed voices (SSSATB), tubular bells, brake drums, harmonium
Duration: 15-18 minutes
First performance: 16 July 2008, Sint Willibrordkapel, Heiloo by VocaalLAB Nederland, during the Karavaan Festival
Commissioned by: Fonds voor de Podiumkunsten+

Program note: The 7 Interludes were written for VocaalLAB Nederland, with the question to compose a set of short pieces ( 2 minutes max each) as 'Verwandlungsmusik' for this specific concert setting. I was asked to make use of the round, pillared dome chapel, and of twelve tubular bells with specified pitches, and a harmonium. Although each of the Interludes starts from these fixed conditions, every piece in the cycle is conceived as its own distinct sound world, evoking the immediacy and presence of the chapel. The 7 Interludes are dedicated to Romain Bischoff, founder and director of VocaalLAB Nederland.

Instrumentation: piano solo and lo-fi electronics
Duration: 10 minutes (Part 1: 4' 30''; Part 2 (Phyllotaxis): 5' 30'')
First performance: 14 May 2008, Nijmegen by Nora Mulder

Program note: À.X. (a hommage to Iannis Xenakis) is closely related to Fern (2006) and Kranz (2005). Dating back from 2005, it was the first sketch in this series of arborescences, waiting for a performer to be finished in this form. In À.X. the sonic equivalent of the Lindenmayer axioma – a fractal-like model of the growth of trees and branches – is presented unfiltered, polyphonic and relentless in the first part. À.X. is modelled after piano pieces by Xenakis – virtuoso repertoire that pianist Nora Mulder plays so powerfully and refined.

The sonic process of growing branches and diverging polyphony is repeated as a choral in the second part (called 'Phyllotaxis', the arrangement of the leaves on the stem of a plant). In Phyllotaxis, a cloud of singing cicadas inhabits the instrument; referring to (in Xenakis' words): "The collision of hail or rain with hard surfaces, or the song of cicadas in a summer field. These sonic events are made out of thousands of isolated sounds; this multitude of sounds, seen as a totality, is a new sonic event."

À.X. is dedicated to Nora Mulder

Instrumentation: string orchestra, percussion, piano and organ/keyboard
Duration: 16 minutes
First performance: 29 March 2008, Concertgebouw Amsterdam by Radio Chamber Orchestra and Thierry Fischer (conductor)
Commissioned by: ZaterdagMatinee, Amsterdam

Program note: "There was an intersection at Main and Hall, and there was nighttime activity that took place within that space… shoplights would come on, and I knew exactly what time they would do so. I also knew what time they would go off. Traffic signals would work — and they had a set time. Cars would go up and down, and they would always stay within the lines of the streets and crosswalks… I knew the taillights would be going in one direction and that the headlights would be in a line someplace else. So I had this universe — outside this place, and there were activities which happened within it, and light and energ y. Then I had a space inside, within that room. A physical confine. It looked out into that space outside through the apertures I had made. Now, I could make openings to accept light in that space or to occlude it." (James Turrell, on the Mendota Hotel Stoppages)

In all of his works, the Light and Space artist James Turrell takes light itself and makes it his material. There is no object in his art, no image, and no point of focus. Aperture is a homage to James Turrell — not in light, but in sound slowly inhabiting the space. Aperture was written for the Dutch Radio Chamber Philharmonic Orchestra and conductor Thierry Fischer. The work was commissioned by and dedicated to Kees Vlaardingerbroek, artistic director of the ZaterdagMatinee series.

Instrumentation: flute, 2 clarinets, 3 saxophones, horn, 3 trombones, piano, percussion, double bass / bass guitar
Duration: 8 minutes
First performance: 30 October 2007, Rotterdam by Orkest De Volharding and Jussi Jaatinen (conductor)

Instrumentation: soprano, mezzosoprano, alto, tenor, baritone and a set of crotales
Duration: 4 minutes (#1) and 6 minutes (#2)
First performance: 21 September 2007, Paris (France) by Compagnie Bischoff

Program note: Referring in part to a missing piece of Ockeghem's Missa Prolationum, Anthony Fiumara wrote his two-part Graduale as a transition from the Gloria to the Credo and from the Credo to the Sanctus. Like Ockeghem, much of Fiumara's work is based on strict number relations. In this case he uses the same principle as a bell ringer might, who strives for the greatest variation in pitches using a limited number of bells. The two parts of the textless Graduale use the same five pitches (a minor scale). The Compagnie sings the first part virtuosically uptempo. The second, stretched-out version is played by the singers on a set of thin-sounding crotale, in remembrance of the bellringer rituals.

Instrumentation: marimba, pedalled percussion, sinus generator and talking performer
Duration: 6 minutes
First preformance: 12 August 2007, Amsterdam by Arnold Marinissen

Program note: Fall #4 is an arrangement of the Laurie Anderson song Walking & Falling. (See Fall #1 for a general note on Ninety-Two Falls)

Instrumentation: prepared timpano
Duration: 6 minutes (minimum)
First preformance: 1 March 2007, 's Hertogenbosch by Arnold Marinissen

Program note: Fall #3 was written as an in memoriam for James Tenney, inspired by his postcard piece Having Never Written A Note For Percussion. (See Fall #1 for a general note on Ninety-Two Falls)

Instrumentation: soprano, mezzosoprano, alto, tenor, baritone
Duration: 7 minutes
First performance: 17 December 2006, Nieuwkoop by Compagnie Bischoff

Program note: Chant was written for a Christmas program by Compagnie Bischoff. The Compagnie needed a piece based on Perotin's Alleluya Nativitas. I took one phrase and voice out of the original and made a five-part canon out of it. Chant is dedicated to Compagnie Bischoff.

Instrumentation: electric guitar
Duration: 13 minutes
First performance: 24 October 2006, Tilburg by Wiek Hijmans

Instrumentation: piano solo
Duration: 9 minutes
First performance: 24 September 2006, Amsterdam by Dante Oei

Program note: Fern is a postscript to Kranz (2005). It uses the same Lindenmayer axiom, of which I translated the first recursions (a slowly growing repetitive structure) to the piano. Fern is dedicated to Dante Boon.

Instrumentation: undetermined percussion instruments
Duration: 9 minutes
First performance: –––

Program note: Fall #2 was written as a travelling work, in which the percussionist can use any instruments he has at his disposal. (See Fall #1 for a general note on Ninety-Two Falls)

Instrumentation: vibraphone, cowbell with pedal
Duration: 5 minutes
First performance: –––

Program note: In all of my works thusfar I've been using 'found mathematical objects': simple automata that form structures in time. Sometimes these structures have a permutative nature (like in Solo for Bass Clarinet), sometines they resemble organic processes (Kranz). These basic organic forms brought on the idea of writing a series of percussion studies dealing with the motion of falling, since falling is one of the most elementary and fascinating time forms we can perceive all around us. The series will be a kind of catalogue of falling, a Kunst des Fallens for one percussionist – of which the parts can be performed seperately, in random groups or as a whole, by one to multiple performers. Why ninety-two? That has everything to do with Peter Greenaway (The Falls) and his interpretation of John Cage (Indeterminacy). Ninety-Two Falls is going to be written for Arnold Marinissen, who immediately saluted this project with enthusiasm.

Instrumentation: bass clarinet and electronic reverb
Duration: 12 minutes (chromatic version), 9 minutes (diatonic version)
First performance: –––

Program note: Solo For Bass Clarinet consists of a complete permutational set of four notes, distributed in turn by permutation over three registers (actually four in total): a hermetic ritual of repetitions-that-keep-appearing-in-a-different-shape. Out of curiosity I made two sketches of the work, a chromatic one and a diatonic one. Surprisingly enough the character of those two versions is completely different: the diatonic version sounds almost harmonic, in the chromatic one the different registers come out more clearly. In the end I couldn’t choose between the two solos — so I put both in this bundle, leaving the choice to the performer. I want an electronic ‘cathedral’ reverb to give the tones and gestures more space — making it sound like a lightly articulated continuum, changing almost imperceptibly and slowly ascending.

Instrumentation: piano, 2 violins, 1 viola, 2 violoncellos
Duration: 11 minutes
First performance: 17 November 2005, Bochum (Germany) by Luxembourg Sinfonietta, conductor Marcel Wengler
Commissioned by: Festival Open Systems, Bochum

Program note: Art is all about form. Forms are represented everywhere – in space, on earth, in nature, in society. One has to be able to read and to understand those forms in order to create something new. In my music I like to use ‘found mathematical objects’: simple automatons which build forms over time. When I encountered Aristid Lindenmayer’s ‘L-systems’ some time ago, I became fascinated with these rules to describe plant forms and growth. The organic development and the self-similarity of the plant forms seemed to be perfectly translatable to music. During my research, I even found the following quote: “Organic form itself is found, mathematically speaking, to be a function of time... We might call the form of an organism an event in space-time, and not merely a configuration in space.” That’s how the idea for Kranz was born: a work that uses a simple Lindenmayer axiom, of which I translated the first five recursions (a slowly growing repetitive structure) to a score for piano and string quintet in five parts. Its harmonic density refers to Ergma by Iannis Xenakis; the articulation of the decaying piano chords in the coda is modeled after Stele by György Kurtág. Kranz is dedicated to my dear friend and composer Willem Boogman.

Instrumentation: flute, oboe, clarinet in b flat / bass clarinet, trombone, 2 percussionists, 2 violins, viola, violoncello
Duration: 12 minutes
First performance: 18 September 2005, Maastricht by Spectra Ensemble, conductor Filip Rathé
Commissioned by: Festival Musica Sacra, Maastricht

Program note: The most eye-catching element in Robert Wylkynson’s Salve Regina (to be found in the Eton Choirbook) are the nine names of the medieval angel hierarchy attached to the nine voices of the motet. It seemed obvious to use that in my arrangement for Spectra Ensemble. But things went altogether differently. I almost immediately recognized a parallel between my arrangement-to-be and Wylkynson’s use of the Gregorian chant Assumpta est Maria as cantus firmus, in the slow moving notes by the tenor. For my part, I decided to use Wylkynson’s motet as a cantus firmus: I squashed his nine-part counterpoint (more precisely bars 185-211, the only place where the complete cantus firmus appears without interruption), stretched it out in time and gave the result to the vibraphone. To complete this process of turning Wylkynson inside out, I took the Gregorian melody and made it into the polyphony of my piece. The result, Lines and Arcs, is a nearly stationary music, consisting of slowly shifting fields. Lines and Arcs is a small homage to composer and inspirator John Luther Adams. The title is borrowed from a wall drawing plan by Sol LeWitt – because in the end, Lines and Arcs is more about patterns, superpositions and canvas than about Wylkynson, or his hierarchy of angels.

Instrumentation: flute, 2 clarinets, 3 saxophones, horn, 3 trombones, 2 pianos, 2 samplers, 1 percussion, double bass / bass guitar
Duration: 23 minutes
First performance: 9 March 2005, Amsterdam by Orkest De Volharding and Jussi Jaatinen (conductor)
Published by: Boosey & Hawkes »

Instrumentation: 2 trumpets, tenor trombone
Duration: 5 minutes
First performance: 20 November 2004, 's Hertogenbosch by Orkest De Volharding (Louis Lanzing and Reijer Dorrestein, trumpet; Johan de Meij, trombone)

Program note: One of the beautiful paintings in the series of homages to Morton Feldman by Dutch artist Ton van Os is called Frozen Time. Van Os' paintings helped me with my own Frozen Time, named after the work that is still an eye-opener for me. Frozen Time is dedicated to Ton van Os, who became a dear friend. It was the music that inspired Van Os to make his series of paintings; which in their turn made me compose this work. And so the circle closes again.

Instrumentation: mezzosoprano, r'bab, oud and percussion
Duration: 4 minutes
First performance: 20 November 2004, Lesce (Slovenia) by Johannette Zomer and Antequera

Program note: Ensemble Antequera are known for their performances of the Cantigas de Santa Maria. Apart from these Cantigas, king Alfonso El Sabio also wrote a treatise on the noble art of chess. For endgame, I projected mediaeval modal scales on the 64 squares and translated them a horizontally with a ’knight’s tour’. A knight’s tour is an ancient puzzle in which the object is to move a knight, starting from any square on a chess board, to every other square, landing on each square only once. The knight's tour I used for endgame is called ’Guy de Chivaler’. It is described in a manuscript in the King’s Library (British Museum), dated c1275 — approximately the same time Alfonso wrote his cantigas and chess treatise.