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For viola and chamber organ
For the composer his introduction to the beautiful tree-like structures visualised in 2D with L-Systems speak of the Gestalt of tree, a treeness more intense and exact than the living object, and able, because of this exactness, to be embedded as a structural mechanism to play in the musical imagination – with or without sounds.
L-Systems built from the axioms used in Treeness.
A Short Introduction to L-Systems
Lindenmayer Systems, or L-Systems, provide a grammar for the construction of self-similar objects through the recusive use of simple substitution rules. For example:
Rules: A=B, B=BA
If we begin with the symbol “A” and then use the above subsitution rules the following sequences will emerge:
A, B, BA, BAB, BABBA, BABBABAB…
Both Treeness and Heartstone use the same set of rules:
Rules: A=BC, B=BBAD, C=CCDA_, D=A__BC
To the left is a graphical representation of these rules. For example: instances of B may interpreted as drawing a line forward, C as rotating 45 degrees, and so forth.
For more information about the use of L-Systems in computer composition please consult the annotated code for Heartstone available to download here.
A guide to performance
The choice of the organ rather than a piano for this chamber work has encouraged a special approach to the notation of dynamics throughout the score. The players are to be guided by the expressive indications that preface each of section of the score and occasionally particular passages and phrases.
The use of the organ encouraged the composer to treat the L-System definitions like the so-called In nomine plainsong taken from Gloria Tibi Trinitas Aequalis found in many early keyboard pieces from The Mulliner Book. Sections L to N make the most explicit reference to this musical world with the viola playing like a viol the L-System definition as a cantus in the middle of the texture. Such references do clearly suggest a particular performance style – very simple registration and lively articulation from the organ and the absence of vibrato and restrained bowing from the viola.
Sections F to K, and O to the end, might be said to provide the very antithesis of such playing described above. The viola is encouraged to play most expressively behind the slow moving chordal textures, making much use of portamento, and the expressive slides and inflections common-place in late 19C and early 20C performance traditions of viola playing (a subject of special interest to the work’s dedicatee)
The chamber organ part was imagined for the Goetze and Gwynn instrument in Clothworkers Centenary Hall at the University of Leeds. This organ has a range of GG to e3 with 8,4 and 2 stops with a Sesquilatra and Cornet.
Performers should not feel restricted to the use of the chamber organ. Other keyboards may be used, particularly the kind of Fender Rhodes velocity-sensitive electric piano found in many of the composer’s works. If a different instrument is chosen, the composer would expect the part to be sympathetically re-imagined by the player.
