Denis Lorrain

Construction 067

Hovering Memories

Algorithmic composition for MIDI piano

(2022, total duration: *ca.* 14 mins)

Programme Note

   No one can predict what evocations a work will awaken. Especially not in the long term. Especially not its author, even if he cannot occult, upon the eve of achievement, the hope that it will arouse some poetic transpositions. However, the work's unpredictable destiny is not a predominant preoccupation in the course of its elaboration. During the creative progression, the mind is mostly occupied with shaping the heaviness of the matter — perhaps does it hope to sublimate it? For lack of better, to conclude the process, remains then the possibility of describing this so lengthily confronted matter.

   This Construction essentially rests on material resulting from nowadays quite usual musical concepts: couples of hexachords form dodecaphonic sequences, which are varied and multiplied through *generalised axial symmetry* operations in a circular representation of the chromatic space. I have used this same basic algorithm in my preceding Constructions 053, "... somewhere south of silence" (2016), and 061, Pleins et déliés (2021). This process originates in a *universe* consisting of the set of all possible couples of all chromatic hexachords comprising all intervals smaller than a tritone (all-intervals-hexachords, algorithm of Jan Vandenheede). A subset of this universe allows to form dodecaphonic sequences, with pairs of hexachords linked by a tritone interval.

   This process is the source of the near totality of the musical elements in the piece. It is here exclusively exposed harmonically, but in various manners, by various algorithms. Ten different dodecaphonic couples of hexachords are put into play. All these couples share one common hexachord — the twenty-first in the order delivered by Jan Vandenheede's algorithm.

   Rhythms applied to this harmonic material are issued from the sturmian sequence of Thomas Noll. In my Construction 047, Eight Sturmian Studies (2015), this sequence was a universal source, generating melodies, harmonies and rhythms. As in subsequent Constructions, it is here restricted to the creation of rhythms for the above harmonic material.

   In contrast with these harmonic and rhythmic materials, another algorithm intervenes in the piece. It was inspired by the deep chromatic "waves" of the beginning of the Ballade n° 2 in B minor (S.171) of Franz Liszt. It is the source of easily recognisable, contrasting musical elements, including violent glissandi.

   The piece proceeds in three movements:

  I — 3'07"

 II — 5'36"

III — 5'18"

DLO

Karlsruhe

April 2022