Isadora Teles De Castro E Costa

Chu-Yin Chen

Sorina-Silvia Cı̂rcu
email: sorina.silvia@gmail.com

Artificial Life within a frame of metacreation on stage

Keywords: Metacreation, performance, interactive digital art, artificial life, scenography, scenography-character, interfaces

In order to investigate the possibilities of co-creation between performer and interactive virtual system, we have developed a scenic installation composed of two parts: the virtual environment and the interaction interface. We offer an analysis of our creative experience from the point of view of the artist researchers in the field of real-time generative synthetic image. Our results show that the creation depends on how the performer perceives the virtual system as well as how he perceives its influence on this system. The creative potential of the system depends on the mechanisms generated and implemented by the artist in a metacreation context and his interpretation of the interaction data. Our perspectives point towards the conception of a scenography-character.

Introduction

Artistic context

The process that produces artistic experiences or artifacts is no longer a secret enclosed in the artist's studio, but a system of creation set in motion by the artist and continued when confronted with the materiality of collective participation, of the spaces of exhibition or of everyday urban spaces. [START_REF] Bishop | Participation[END_REF], [START_REF] Popper | Art, action et participation: L'artiste et la créativité aujourd'hui[END_REF] The digital arts have been developed thanks to the advent and popularization of technological tools. They emerge as a transdisciplinary approach between design, computer science, complexity sciences, biology, and artificial life. The creative processes have become technological. [START_REF] Couchot | L'art numérique[END_REF] In the context of participatory works, the viewer becomes an actor in the work and potentially a performer, who can even interact remotely. [START_REF] Dixon | Digital Performance: A History of New Media in Theater, Dance, Performance Art, and Installation[END_REF] The type of interaction is no longer responsive but can be adaptive, conversational, and creative, between machines and participants. [START_REF] Edmonds | The art of interaction[END_REF] The literature gives examples that an evolving virtual ecosystem can be creative or that this type of self-organizing system can demonstrate an emerging potential allowing it to improvise with a performer. [START_REF] Mccormack | Creative Ecosystems[END_REF], [START_REF] Penny | Improvisation and Interaction, Canons and Rules, Emergence and Play[END_REF] Some developer-artists seize the computational capabilities of the graphics card in an alternative way to create complex systems and use artificial life algorithms, giving rise to emerging behaviors and impressive endogenous interaction phenomena. [START_REF]Physarum -Sage Jenson[END_REF], [START_REF] Softologyblog | Physarum Simulations[END_REF] Other developer-artists create or hack interfaces using electronic sensors or mobile devices to establish a tangible, intimate and active relationship within the technological social context and connected networks. [START_REF] Stocker | Interactive Art Research[END_REF] Through such interfaces, artists seek an adaptive and dialogic, conversational engagement between the participant and the virtual system, in order to investigate possible relationships with the machine and to express the uncertainty of existence through the uncertainty in the work of art.

For Whitelaw, the conception of a generative, evolving, interactive system is one of the characteristics of an artwork that can be described as autonomous. He refers to this method of creating digital works by the term metacreation. [START_REF] Whitelaw | Metacreation: Art and Artificial Life[END_REF] Such a system contains parameters of appearance and behavior which can be modified according to the interaction with the external environment to the virtual, what Bret calls the sources of exogenous interaction that complements the endogenous interactions which occur between the components of the virtual system. [START_REF] Bret | VIE ARTIFICIELLE ET CRÉATION ARTISTIQUE[END_REF] This dynamic diverges from the initial instructions given by the artistdeveloper and may result in unpredictable behavior occurring during the processes. It is regarding this meta creative process that we will assess the creative potential of the virtual part of our scenographic proposal.

Project Co-évolution, Co-création et Improvisation Homme-Machine (CECCI-H2M)

The research-creation process described in this article is part of the Co-évolution, Co-création et Improvisation Homme-Machine project, led by Chu-Yin Chen: that investigates ways of sustainable behavioral coevolution with emerging human-machine co-creation. The project proposal merges two research-creation approaches through practice. That of the artist-researcher Silvia Cîrcu, who studies the choreographic interactions between performers and robots. And that of Isadora Teles, which aims to establish a dynamic of improvised co-evolution between performer and evolving virtual system. This article traces and analyzes the experiments carried out by the two researchers during two artistic studio residencies, from the point of view of the artist developing the virtual system and its interfaces with the scene.

During their experiments, the artist-researchers compared their artistic proposals to find convergences and clarify their intentions and ideas. The common goal was the conception of a co-created performance on stage between the performer, an HRP-4 humanoid robot and an interactive evolving virtual ecosystem. It was also a question of characterizing what the possibilities of co-creation between the performer and two types of artificial entities would be, when those artificial entities are either embodied or not embodied on stage.

The project also aimed to question the design of autonomous and evolving creative tools for performance with the intention of staging an improvisation for the performer and his alter-ego taking the form of an evolving virtual ecosystem. Our hypothesis to establish a dynamic of creative collaboration was that the development of an autonomous and evolving ecosystem would be embodied and therefore would assume a physical form on stage, being able to influence the performer's gestures (Fig. 1).

Experimentations Experimental Plan

The experimental plan to set up a creative and improvised interaction between performer and artificial entities consist of:

• Developing, separately, three prototypes of "species" for the virtual ecosystem as well as their mode of intra-species interactions. • Developing three interface prototypes for interacting with elements on stage and embodying the same virtual system in the form of objects that can be manipulated, played, and penetrated by the gestures of the performer. • To study the possible co-creative and adaptive interaction relationships between each "species" of the virtual system and the performer.

The aim of the proposal was to use metaphors of emotional states to imagine the shape and behavior of the different species that would inhabit the virtual world. The technical goal was to find ways of expressing and giving the sensation that, by their form and by their behavior, each species is possessed by or acts according to one of the emotions mentioned. Once the shapes and corresponding behaviors were clarified, the next step was to create and test the algorithms that could correspond to such sensitive expressions.

Creating a graphical simulation of a complex system must consider the technical challenge of animating and making many autonomous elements interact. This requires considerable computing power, which increases exponentially with the number of individuals. Therefore, the development of the virtual universe was carried out using mainly the technique of image synthesis by shaders.

The shaders enable the programming of the graphics card to generate images by calculations performed in parallel. [START_REF] Vivo | The Book of Shaders[END_REF] We have experimented with fragment shaders and then with compute shaders. Compute shaders allow us to get complex image and behavioral animation qualities which are difficult to achieve by other techniques, because they exploit the computing power optimized by the graphics card.

An important reason in the choice of technical tool was the existence of examples of simulation of common biological phenomena with the subjects treated by artificial life using such technique.

Compute shaders are used for scientific simulation as well as for bioinformatics and simulation of complex dynamical systems. [START_REF] Dematté | GPU computing for systems biology[END_REF] However, such references in the artistic field are rare and steps of taming and technical adaptation are required.

Virtual environment

Particle system with fragment shaders

The first prototype was designed to express the "dream" or the state of reverie. To do this, we have conceived a type of behavior which shows wandering flight, expresses a lightness in the movements and would be contrasted with another species which would represent "fear". This behavior leads us to think of the imaginary flight of fairies, a dance of birds or leaves heaving in the wind.

To set up this system of "imaginary fairies", we started by programming a particle system using fragment shaders, within the touchdesigner software. Fragment shaders make it possible to deal with many dynamic pixel data, but there can be no interaction between them, nor exchange of information.

The components of the particle system have basic properties of physical simulation, such as mass, velocity, and lifetime. They are influenced by forces external to the system, which can attract and guide them. An interesting aspect of the behavior of this particle system is that, if we increase the particles' scale and the force of attraction, the collective behavior becomes an organic mass concentrated on a flow of force. This shape, green on a red background, is reminiscent of a pulsating organ (Fig. 2). This particle system behavior was not inspired by cell behavior, but it has emergent collective properties vastly used to model dynamic natural phenomena. [START_REF] Sims | Particle Animation and Rendering Using Data Parallel Computation[END_REF] In our case it behaved like a pulsating organism or animal organ thanks to specific behavioral parameters explored through the process of improvisational interactional and "tweaking" on stage.

The void in the background of the virtual environment suggested an organ in preservation in a jar, isolated, but still "alive" (Fig. 2). The sensation of a living organ was due to the unstable movement of the system and therefore of the emerging collective form. This instability of the shape was caused by the data obtained from the capture of the performer by the Kinect, which controlled parameters inherent to the particles such as their maximum speed, their mass, and the constants of attraction towards the attractors. This phenomenon of data instability was the positive cause of the pulsating impression of the particle system organic form.

Particle system with compute shaders

Our second experiment was the modeling of a particle system whose position information was calculated by a compute shader. The change in technique was aimed at establishing an endogenous interaction among the particles and with the virtual environment. For studio residences, the particles could not be perceived among themselves.

The difference between compute shaders and other types of shaders (vertex, geometry, and fragment shaders) is that they do not fit into the render pipeline. The compute and the fragment shader have similarities, but they were designed for different purposes.

The compute shader allows us to use the GPU to perform calculations that are not necessarily related to 3D or image processing. This is the so-called GPGPU technology for General-Purpose computing on Graphics Processing Units.

In our case, we used it to calculate the position and velocity of a particle system guided by a mathematical function that generates organic flow, which can be used to simulate fluids.

We were inspired by the systems of particles moving in a Curl Noise. The technique is often used for dynamic nonautonomous systems such as fluid simulation or the displacement of the sand. In our case, we used it as a wind force to guide the particle movement. The wave variations and their organicity helped us get a prototype of the aimed behavior : an impression of a self-organized multi-agent system [START_REF] Dematté | GPU computing for systems biology[END_REF], [START_REF] Bridson | Curl-noise for procedural fluid flow[END_REF] (Fig. 3) We tested the interaction between the performer's motion capture data and the second prototype of the "Dream" species. Two joints of the performer were linked to two behavior parameters of the particle system. The elbow position controlled the direction of the Curl noise that guided the movement of the system, and the knee position influenced the direction of the noise and the friction, that is, the damping of particle velocity.

These interaction links allowed an interesting synchronization between the movement of the particles and the performer's gestures. This occurred because we were able to identify a notion of rhythm in the intervention in the friction of the particles and the fact that the movement of the arms influenced their direction, giving the impression of a dance master to the performer.

Cellular automata with compute shaders

The second species that would integrate the virtual ecosystem represents "fear". Our main issue was to find a way to create a type of virtual agent that leaves patterns and traces on a surface by its growth or by its displacement to represent fear as something that spreads out on surfaces and that leaves traces. Traces of infectious and unhealthy appearance, and whose appearance is reminiscent of mold.

We were inspired by the modeling of the behavior of Physarum polycephalum, a single-cell organism that can exhibit the formation of complex and emerging growth patterns. [START_REF] Jones | Characteristics of pattern formation and evolution in approximations of physarum transport networks[END_REF] The first step in modeling such behavior was first to set up a cellular automaton system to establish the basis of an optimized algorithm for endogenous perception and interaction between virtual individuals. This method is suggested by Arsiliath in his Psychobiotik workshop 1 where the goal is to build a complex system of autonomous agents with compute shaders. Two variations of the cellular automata were tested. One based on the concept of cyclic cellular automata and the second based on Langton's Edge of Chaos article. [START_REF] Fisch | Cyclic Cellular Automata in Two Dimensions[END_REF], [START_REF] Langton | Computation at the edge of chaos: Phase transitions and emergent computation[END_REF] The peculiarity of the cellular automata algorithm is that, depending on the combination of parameters of interaction behavior with neighboring cells, it can generate a large amount of different emerging patterns in a complex way and therefore difficult to predict by the artist. One would have to manually test a wide variety of different rule combinations to visualize the possibilities and choose a specific type of behavior corresponding to an intention, in our case, the internal emotional state of the performer.

The plethora of pattern possibilities emerging from several interacting entities is one of the issues studied by genetic algorithms (exploration of "landscapes" or "landscapes" of possibilities), especially when they are used as an aesthetic evaluation technique in interactive generative processes. [START_REF] Sims | Artificial Evolution for Computer Graphics[END_REF] However, during the interactive experience, the performer explored this landscape of possibilities through his gestures, in a negotiation between the intention of his movement and the projected pattern that formed in response to the behavior generated by automata's evolutionary rules, conditioned by the position of the joints (elbow and knees) of the performer (Fig. 4).

Conclusions about the virtual environment

The development of a particle system through fragment shaders was a stage of learning and appropriation of the technique. The system was used during the experimentation with the performer and opened aesthetic perspectives for further development of autonomous agents.

Once the technique for calculating particle behavior with the fragment shader had been entered, the use of texture buffers and separately rendered geometry instances allowed us to switch to the compute shaders to perform the calculation of virtual environment elements behavior.

The cellular automata algorithm was used as an intermediate step in the appropriation of the technique of building a base algorithm optimized for the creation of endogenous interactions. However, in view of the interesting patterns that emerge dynamically according to the exploratory exogenous interaction modifying endogenous interaction rules, this algorithm will be used as a component of the virtual ecosystem.

This will require an assessment of the expressive and poetic function of the patterns and an assessment of the interaction in the context of the artistic intention to express the internal state of the performer. The discussion is ongoing, but it should be noted the possible addition of a new kind of emotion to the virtual ecosystem following the experiments in the studio.

In the case of the prototype which aims to represent the state of "dreaming", the intermediate stage of development has also instigated thoughts. The particles produced with the fragment shader showed us the plastic potential of such a technique for building systems. We may use distinct levels of autonomy in qualifying different types of virtual individuals. However, a physical simulation operation without collision limitations and a degree of autonomy, can also prove to be a rich source of raw material for the creation of geometric shapes and masses in interaction with the performer. The variation in autonomy levels among the types of virtual elements was important to have a more malleable species, such as a kind of digital clay or a raw material that could be turned, like a vase on a potter's wheel. For the potter, although clay is not an autonomous or living material, it nevertheless presents physical properties and possibilities of plastic derivation rich in creative potential when it is modeled and glazed.

Likewise, the potential for plasticity of the particles' behavior, that were attracted and recalled by the symbolic representation of the performer in virtual space, made us question the condition of the autonomy of a virtual material conducive to creation. How exactly is a virtual simulation of clay matter, for example, more or less fruitful to co-creation than the simulation of a collective of ants or cells, when manipulated or influenced by a performer?

Interaction interface

Tested hypothesis

First, we designed an electronic collar that captured the acceleration data of the perforator and transformed it into a rhythm of luminosity by means of two strips of LEDs.

Nonetheless, the interaction with the collar was not perceptible by the performer and this fragile structure did not adapt well to the performer's movements (Fig. 5). Given the priority of connecting his gestures to the virtual system, we conducted interaction tests by capturing movement with the camera of a Kinect. This allowed us to have fruitful interactions and gave us some leads about the links that the gestures could have with the virtual system. The interaction with the Kinect provided us clues on the plastic potential of virtual forms and their ability for enjoyment by the performer (Fig. 5). Despite interesting interaction experiments with the Kinect, we wanted to keep the possibility of allowing the performer and director to improvise with sensitive interfaces. To explore the creative possibilities of the incarnation of the virtual on stage, the creation of sensitive stage objects that can be manipulated and played was important as a hypothesis to allow us to have a margin of movement in terms of layout in the stage and on the performer's body (Fig. 6).

Prototype 3: Communication between connected mobile devices and virtual system

To test our hypothesis of a modular, fragmented, and sensitive scenography, we needed connected devices allowing reliable communication and resistance to the movements and gestures of the performer. We therefore considered devices linked to mobile technologies as a hypothesis to solve this problem.

We have tested the portable device interaction hypothesis during the second studio residency (Fig. 7). During our experiments, the performer had to hold the devices limiting his movements. For the on-screen drawing interaction, the performer had to look at the screen of the portable smartphone. We do not yet know if this constraint of movement limitation is an interesting creative path, but, although this limitation seems unconstructive to the dancer, it reflects quite faithfully our daily use of portable devices.

Conclusions about interface interaction

The use of this portable device by the dancer on stage led to the following observations:

On the one hand, the public or anyone connected to the web server could act as an attractor to the behavior of the virtual environment, partially controlling it from their smartphone. This is part of a process of active participation of the spectator in the performance. On the other hand, we could use multiple cell phones, which are more easily accessible to create connected objects or costumes. The function or the appearance of these smartphones would thus eventually be "recycled".

In our co-creation context, the exploration of the creative possibilities and the potential gestures that these portable devices allow remain to be deepened during a next residency together with an evaluation of the theoretical issues that their use gives rise to. For example, if we fix them on parts of the performer's body, what type of movement can the sensors of the portables acquire and make usable by the virtual system? The interaction by their sensor motivates an original use of cellphones or would daily gestures persist?

Results

For Whitelaw, metacreation as an artistic technique is theorized as a creator method itself, because the artist creates a creative process: "Familiar tropes of endless novelty and metacreation reappear; often the works are somehow autonomous; once made, they make themselves". [START_REF] Whitelaw | Metacreation: Art and Artificial Life[END_REF] This creativity is developed in a different timeframe than the one we planned to study. Prior to the establishment of a co-creation between the virtual system and the performer, there is a co-creation stage between the artistdeveloper and his generative system that must be considered. In order to be able to characterize the emerging aesthetic phenomena that result from the functioning of the virtual system in interaction, the creation of a vocabulary specific to the generative system and to the performance.

The ability to describe a moment of creation and adaptation between the performer, the artist-developer and the generative system turned out to be necessary in our case study.

Although we have developed several types of virtual systems, they took on new meanings and those new issues arose during the studio experience. Prior to the establishment of a potentially autonomous and emerging system, the question of the perception of virtual autonomy by the performer as well as the physical characteristics and conditions of communication by the interface are important aspects that must be tested in situ. These are variables that can promote or jeopardize performance, and therefore, cocreation.

The hypothesis of creating an interface began with the idea of having a means of exchanging data between the stage and the virtual environment. Its appearance and operation have been designed to respond to artistic intentions and to the metaphor of the representation of emotions. Very early on during our experiments in the studio, we realized that their presence on stage fell within a broader framework than that of communication with the virtual ecosystem. We were confronted with the staging intentions and with the construction of the meaning of performance in general (in contrast with the sense of the virtual in isolation). The projected virtual environment and the interface became the scenography of the performance and therefore had to be considered together with the means of perception of the scene by the performer.

We developed some of the interfaces during the studio experience and tested them in the initial phase. This experience allowed us to direct our expectations and assumptions based on the materiality of the stage and the performer's body; the creation was therefore more applied and more suited to the desired artistic situation. The constructive or ineffective constraints of movement, induced by interfaces, were identified from interaction observations made in the studio. They allowed us to consider the performer's movement in a precise way according to emerging hypotheses about the interface and embodiment of the virtual on the stage.

Through conversations and an interview with the performer, we noticed that the perception of co-creation (expressed by the performer as a perception of the autonomy of the virtual during interactions with autonomous entities) was more present when the interaction was simpler, clearer, and more responsive by the performer. This impression might be explained by the stage layout which was not very ergonomic or not very consistent with the idea of an exploratory and improvised creation with the virtual system. Indeed, the image of the virtual ecosystem was projected on a screen located behind the dancer and by which he was implicitly attracted. This generated a form of confusion or conflict of attention linked to the sharing of focus between the bodily creation of the moment and the follow-up of the exploratory interaction with the virtual. For the performer, the dynamic lived between that of being a spectator of an interactive installation and that of a dancer who focuses on his presence and his expressive gesture on stage.

This shared attention between the real and virtual environments turned out to be unconstructive and therefore uncreative. This observation made us consider the possibility of spatializing the projection on the stage, by means of a projection on the fabric of the performer's costume (Fig 8). The first impressions of this ongoing test are already promising. They outline a path towards the resolution of the problematic of the interaction by the perception of the scenography. This scenography attracts the performer's commitment to the co-creation. The problematic of the perception of the scenography by the performer lead to the hypothesis of creating a scenography-character incorporated into the scene as a staged element. Such a hypothesis is as important a condition for co-creation as the construction of an autonomous evolving virtual ecosystem. Moreover, if the virtual system is not perceived as autonomous or if it is not perceived at all, how can it be in creative dialogue with the performer?

Discussion

Our experimentation in the studio gave us clues to understand the conditions conducive to co-creation in three key aspects of the scenic environment conception: the scenography (how the performer and the audience perceive the virtual), the interface (how the virtual perceives the "real") and the programming of the virtual system (creation of the behavior of virtual entities and of its endogenous and exogenous interaction modalities).

In view of the prototype state of species and interfaces, at several times the artist developer intervened to calibrate the interactions, test new relationships between the collected data and the parameters to improve the configurations of the virtual system. The presence of the artist-developer as an operator or mediator in the relationship between the performer and the generative system was studied within the INREV team and represents a concept and a model in its own right, within the dynamic of co-creation between the participant and the interactive device. [START_REF] Rémy | Game jockey as an intermediary between DJ practice and video games[END_REF], [START_REF] Plessiet | MITMI Man-In-The-Middle Interaction: The human back in the loop[END_REF] The sensitivity and perception of the mediator enter as a variable in the evolution of performance.

The concept of performance co-created between mediator, performer and generative system gives us indications on how to incorporate a virtual system on the stage. Can or should this type of hybrid scenography have a mediator? Can he participate in the performance while being on stage? The operator's mediation on the perception of the performer's data by the virtual system could be used in the design of an evaluation function (fitness function) aiming to characterize the adaptability of the virtual system and its species as part of the implementation of an evolutionary step by genetic algorithm.

The studio development experience allowed us to consider the performer's expectations and needs and helped us build an emotional bridge between him and the virtual system. An added step in the interaction experience plan was the familiarization with the functioning of the system, during which the artist-developer explained to the performer how the system worked, how it was developed, what were his inspirations and what were the links that united the simulations or algorithms of artificial life described in many publications and the digital art systems created on these principles. After this introduction, the performer was able to forge subjective links with the virtual and led the interactions based on his new knowledge.

The learning and exploration phase have been shortened and new clues for co-creation have emerged, which Edmonds calls the adaptation and dialogue phase. [START_REF] Edmonds | The art of interaction[END_REF] A need of the performer was to perceive his influence on the rhythm of the particles. She felt that this influence existed at times and waned at others. The moments when she rediscovered this interaction became moments of creative awakening, driving new gestures. This need expressed by the performer motivated the start of the creation of a common vocabulary, mentioned in the Results section of this article, which served as a bridge between the programming of the virtual environment behavior and the scenic vocabulary of dance. This need manifested by experience suggested the idea of introducing parameters into the behavior of virtual entities that could be identified as the "rhythm" of the virtual by the performer. How to identify dance phenomena in the language of virtual autonomy simulations to make the interaction clearer and more constructive with a view to co-creation? Other concepts from the vocabularies of the modeling of complex systems and of performance were exchanged such as: autonomy, incarnation, form, flow, among others, for which links will be built and discussed during the next studio experiments.

At the end of the first residency, we presented an excerpt from our experiments and received constructive feedback from the Centre des Arts d'Enghien-les-Bains and INREV teams. As spectators, they problematized the surface of the projection as well as the way in which we staged this projection. During a team discussion, we realized that this problem was also perceived by the performer and could thus be formalized from the angle of the perception of the virtual environment by the performer: how a specialized and fragmented scenography in space, not only at the level of the interfaces, but also at the level of the projections, can it contribute to a better perception of the scene and therefore encourage a dialogic / adaptive improvisation on the part of the performer?

This feedback was considered for the second round of studio experiments, when we tested projections on fabric in space and on the performer's costume. The new environmental specialization tests have been promising and are in line with our goal of building co-creation conditions.

Conclusion and Perspectives

The goal of designing a scalable virtual ecosystem quickly shifted to creating the virtual environment and building some form of onstage incarnation to support the performer's adaptive engagement. Our new research-creation hypothesis is to develop the evolving virtual environment so that its incarnation on stage allows spatialized perception and interactions with the performer. If we want the scenography to be played, touched, and manipulated by the performer, but also to be autonomous, acting and reacting to the stage environment, that supposes that it becomes an actor on stage. We call this conformation a scenography-character.

The dialogue will be established not only by the attention that the performer pays to the virtual environment projected on a screen or on himself, but also because in inhabiting the stage, the virtual induces constraints but also the suggested possibilities, which are as many attempts to confront these two elements.

The expression of emotions was initially implemented by following a process of metaphoric and analogical description of emotional sensation, and by transcribing it through virtual movement from the point of view of the artist-developer. But these descriptions were changed during the studio experience thanks to observations and exchanges of ideas with the performer in an improvised situation. In this case, the expression of emotions by the entities is co-created at the level of the initial programming of the behavior of the virtual entities, within the limits of the emotion-behavior metaphor set up by the artist-developer. The scenography intends to express the alter-ego of the performer during an evolutionary transformation; its implementation will be our next work step.

The studio experience also caused the adaptation of goals and methods development of the virtual system and of the interaction interfaces, considering the limitations of the initial proposals through the materiality of the experience, the expressive needs and intentions of the performer / director and discovering the weak points and new potentials of the creation when it is put in a situation.

The characteristics of the hybrid scenography described in the article make us think of the possibility of interpreting the design of the scenography in a way integrated with the conception of the staging, by improvisation and by experimentation in the studio, in the form of a scenographycharacter.

Figure 1 .

 1 Figure 1. Two different sketches representing our conception of the three elements of the stage together: performer, interface, and scenography. ©Isadora Teles de Castro e Costa, 2021

Figure 2 .

 2 Figure 2. Recurring shapes during our experiments. Organ-like mass of fragment shader particles are depicted in green. ©Isadora Teles de Castro e Costa, 2021

Figure 3 .

 3 Figure 3. Choreographic exploration in interaction with compute shader particles. The performer modified the parameters of a curl noise function. The noise guided the movement of the particles. ©Isadora Teles de Castro e Costa, 2021

Figure 4 .

 4 Figure 4. Choreographic exploration in interaction with compute shader cellular automata. The performer's movements modified the parameters of the systems' behavioral rules ©Isadora Teles de Castro e Costa, 2021

Figure 5 .

 5 Figure 5. Two moments of experimentation with the Kinect (left) and with the electronical-interactive necklace (right) ©Isadora Teles de Castro e Costa, 2021

Figure 6 .

 6 Figure 6. Two different sketches representing how we imagined the interactive interfaces being manipulated by the performer ©Isadora Teles de Castro e Costa, 2021

Figure 7 .

 7 Figure 7. Experiments of choreographic interactions with fragment shader particle system through the manipulation of a tablet. ©Isadora Teles de Castro e Costa, 2021

Figure 8 .

 8 Figure 8. Experimentations with the projection of particle simulations over white and translucent fabric ported by the performer ©Isadora Teles de Castro e Costa, 2021

"arsiliath (@arsiliath) / Twitter," Twitter. https://twitter.com/arsiliath (accessed Oct.

[START_REF] Plessiet | MITMI Man-In-The-Middle Interaction: The human back in the loop[END_REF] 2021).

Acknowledgements

This work benefited from the support of EUR ArTeC and from the assistance of the French State generated by the National Research Agency under the future investment program bearing the reference ANR-17-EURE-0008.


Isadora Teles De Castro E Costa

Hui-Ting Hong

Chu-Yin Chen
email: chu-yin.chen@univ-paris8.fr

A Performance Co-Created with an Autonomous Virtual System: A Symbiotic Approach

Keywords: Performance, Artificial Life, Autonomy, Symbiosis, Co-Creation, Unexpectedness, Real-Time Computer Graphics

This paper is a case study of a performance co-created in interaction with an autonomous virtual system. Our outcomes point to an essential production period where the creative team learns to know the virtual system through indirect interactions: the match-up phase. During this step, co-creation and coevolution moments happened, indicating a possible symbiotic relationship. We discuss the implications and the outcomes of working with autonomous scenography in a performative context. We then expand the reflection to the potential creative associations between performance arts and autonomous technology.

Introduction

This paper is a case study of experiments carried out in the context of the project CECCI-H2M ("Co-évolution, cocréation et improvisation humain-machine"). We will talk about a specific experience with a virtual ecosystem and about the creative process that enabled us to explore our research question: how can a performance be co-created with an autonomous virtual system?

We are interested in constructing virtual autonomy in the search for scenographic improvisation through the emergence of virtual patterns and behaviors. However, what is autonomy in the context of digital arts? An autonomous computational artifact, as described by Baljko and Tenhaaf: "has some sort of internal state space, it outwardly manifests information as to its internal state (...), and its behavior depends on its state" [START_REF] Baljko | The Aesthetics of Emergence: Co-Constructed Interactions[END_REF]. Similarly, Bishop and Erden define that "an autonomous system is typically considered to be a self-determining system, as distinguished from a system whose behavior is explicitly externally engineered" [START_REF] Bishop | Computational Creativity, Intelligence and Autonomy[END_REF]. In short, we could define autonomous computational artifacts as entities with an apparent internal motivation (internal self-determining state) that guides their behavior prior to the influence of external forces.

According to Maturana and Varela, autonomy is a condition for a "living machine" and relates to the notion of autopoiesis, that is, self-fabrication [START_REF] Maturana | Autopoiesis and Cognition: The Realization of the Living[END_REF]. The independence of the artwork from the artist's control tends to transport it to the realm of the living, at least as an artificial form of alterity or impression of Life. In the study of complex systems and within the domain of Artificial Life, the concept of emergence accounts for a surprising phenomenon, often linked to creative solutions. Using the simulation of complex systems inspired by nature, artists move from the creative process to the metacreative process: the design of autonomous mechanisms that, in turn, create artworks or artistic situations. Following this reasoning, Whitelaw [START_REF] Whitelaw | Metacreation: Art and Artificial Life[END_REF] examines how artists have been inspired by Artificial Life to pursue emergence due to the agency, novelty, and creativity in biological, chemical, and multi-agent processes.

Within a second-order cybernetic point of view, Couchot, Bret, and Tramus defined the artifact autonomy in connection with its aptitude for self-organization and to afford interaction in different environments: endogenous and exogenous. According to them, an autonomous artwork behavior is qualified by endogenous interactivity, which handles the dialogue among the virtual objects, able to perceive specific characteristics from each other and keep relationships more or less complex. The autonomous virtual system can also be open to the perception of its environment in a "second-order interactivity", in analogy to second-order cybernetics. Beyond the engagement between the participant and the artistic process through an interactive interface, second-order interactivity would appear when the autonomous system can modify itself during a learning process by interacting with its environment to adapt to it. The participant is encouraged to explore aesthetic possibilities when embedded in a reciprocal, emergent, and unforeseen interactive context. Depending on the interaction interface setup, the means at his disposal for this exploration enables gesture experimentation, movements, and creativity, in the search for communication or understanding [START_REF] Tramus | La seconde interactivité[END_REF].

In our practice and research, the application and discussion around Artificial Life are considered in the performance art context and connected with unpredictability. Inspired by Edmond Couchot's question [START_REF] Couchot | Automatisme, autonomie et esthétique dans les arts vivants[END_REF] about "how does the machine create the unpredictable on stage?" we intend to study autonomous virtual systems based on the simulation of complex organic systems within the performance context to promote a new sense of unpredictability and improvisation.

Bringing a performer into a confrontation with an autonomous virtual and perceptual system encourages emergent phenomena and motivates improvised reactions. Our hypothesis is based on establishing this interaction dynamic as a possible way or method of emergent narrative creation, built during the interaction in a co-creative way. This method can indicate a symbiotic phenomenon with an artistic purpose and shed light on new ways of scenic composition with new technologies. As researchers and designers of virtual systems, we imagine methodologies and concepts about the associations between autonomous virtual systems as improvising presences and the living arts. We wonder: How can the performing arts take advantage of autonomous virtual entities in the quest for new ways of imagining the stage space and the performance? How to articulate new ways of conceiving dramaturgy and being inspired? How can unpredictability be used to express contemporary emotions and concerns?

Methodology Research Questions

The methodological problem that encouraged this project is divided into two parts. First, how to create an interactive virtual system to promote co-creation on stage? Second, how to cooperate with this system while composing a performance, aiming for a creative relationship between humans and machines?

We chose to develop an evolving virtual ecosystem to solve the first problem. This choice is due to the leads in the literature about artificial life algorithms and their potential to represent or generate emergent and unexpected aesthetic phenomena. On the other hand, we chose the performance medium to answer the second problem through the performer's persistent and attentive improvisation vis-à-vis her environment. Our main goal during the experimental phase of the artistic experimentation was establishing an exploratory exchange between the performer and the virtual system, keeping the autonomy of the two partakers and, therefore, their potential unpredictability to bring out a performance that shows a mutual improvisation process.

Research Hypothesis and Interaction Setup

The experiments of the research-creation project described in this article are the continuation of the experiments of last year described in the article [START_REF] De Castro E Costa | Artificial Life within a frame of metacreation on stage[END_REF]. Iterating last year's reflections and inspired by leads in literature and electronic digital art, such as the cases of the creative ecosystems of Jon McCormack [START_REF] Mccormack | Creative Ecosystems[END_REF], we have created an evolving virtual ecosystem as an essential tool for testing the hypothesis of a creative dynamic between human and machine. Concerning the interface, we hypothesized that an "indirect" interaction (Fig. 1) would make the interaction dynamics more exploratory and keep the autonomous (or independent) character of the two types of entities in dialogue, real and virtual. We move from a first-order (responsive) to a second-order (adaptive) interaction. The ideas for the performance would accommodate themselves to the progressive aesthetic discoveries enabled by the interaction with the autonomous virtual system.

We based the design of our experiments on developing the foundations of an evolving interactive program to be tested and improved during the artistic residency. We then conducted interaction tests to verify how our creative expectations and the virtual behavior styles fit.

Core Co-creation Process

The main result of our research-creation residency was the provision of a methodology for developing, managing, and interpreting a virtual autonomous scenography in the context of the living arts. This methodology involves match-up phases through interaction with the virtual system in a receptive way to emerging aesthetic possibilities by the entire artistic team. We, therefore, achieved a co-created performance in 4 steps:

1. The development of an evolving virtual ecosystem (E.V.E.)

considering the performer's presence and the researchcreation goals (co-creation and co-evolution).

2. The match-up phase, by the art director, of the behavior and appearance of the E.V.E., understanding how it works, and exploring the various points of view and approaches to the system.

3. The phase of matching up the E.V.E. by the performer, exploring the aesthetic potential from the interaction between her movements and the system's behavior.

4. The match-up phase of the E.V.E. by the developer and stage manager once the directives of the artistic direction are established, and the intention of the performance is solidified.

Experiments with E.V.E.

The first step in exploring the issue of co-creativity was creating a virtual system capable of manifesting surprising, emergent, and "creative" behaviors and patterns regarding our expectations and concerning the initial state of the visual explorations [START_REF] Cariani | Emergence and Artificial Life[END_REF]. We have envisioned the different behaviors of our virtual ecosystem through the planning methodology of an agent-based model 1 . Then, we identified some simulations that were sensitive to their virtual environment, autonomous, and with types of movement close to those we expected to perform virtually. Inspired by the idea of simulating complex self-organizing systems, we used algorithms from the field of Artificial Life, more specifically from artists and researchers who work with speculative biology or synthetic biology. Finally, we adapted the chosen biological simulations to our artistic desires and associated the resulting behaviors with a second-order interaction with the creative team.

E.V.E. Development

We experimented with the design of a first species based on the research and reports of Arsiliath 2 and Sage Jenson 3 , who were inspired by Jeff Jones's publication on Physarum transport networks [START_REF] Jones | Characteristics of pattern formation and evolution in approximations of physarum transport networks[END_REF]. It is a combination of two behaviors: ant foraging and the movement and growth of the Physarum. This first species can perceive its surroundings with a limited angle and distance. Therefore, each agent checks the neighboring pixels to measure the quantity of "pheromones" present, represented by colored lines left by the trajectory of agents of this species. Where there is a significant quantity of pheromones (intensity of R, G, B in the neighboring pixel), the agent will assume as its next destination, forming moving patterns of agents. The emergent aspect of the pattern created by the collectivity of entities is reminiscent of the patterns created by the movement and growth of the Physarum in search of food.

The second species was based on the boid's flocking algorithm [START_REF] Reynolds | Flocks, herds and schools: A distributed behavioral model[END_REF] [10]. To move, the agent measures its neighbor's speed, direction, and position to calculate its speed and direction, intending to align its trajectory, separating from neighbors so as not to hit each other and maintain cohesion in the speed of movement. This technique allows agents to form concise groups according to the angle of view, the extent of perception, alignment, separation, and cohesion.

The third species is inspired by the behavior of random walkers, where agents move according to a random direction. We used a probability technique to make their movement random but biased in the direction of a target. The target or attractor, in the case of all three species, is the position of the food. First, we created food points generated according to a four-dimensional "Hermit" type noise. Food attracts agents with less energy, nourishes them, and repels agents with high energy.

Once the species' behaviors were created (Fig. 2), we brought them together in a single virtual environment and created the interactions between them. Agents could perceive and guide each other, regardless of species. Then we set up the ecosystem dynamics with genetic algorithms. We linked the main behavior parameters of the agents to 4 genes, corresponding to the values of R, G, B, and A in a texture buffer which kept the D.N.A. of each agent. See Table 1 for an illustration of the correspondence between each "gene" and each species parameter.

Agents had an initial amount of energy that increased with contact with food and decreased as the agent moved away. The agent needed to have a minimum level of energy (called health in the program), check if there is an equally healthy neighboring agent, and count with a probabilistic decision to reproduce. If the decision is confirmed, the two entities' D.N.A. is crossed (crossover) with a mutation rate, and a new agent is created in a free space. If an agent's energy level is too low, it is disabled and ignored in updating the parameters of each pixel of the input textures (death of an agent in the system). See Fig. 3 for the general functioning of the virtual ecosystem.

GENES

Compute Shaders

Arsiliath, in his Psychobiotik course, proposes an optimized algorithm to realize a multi-agent system with compute shaders in Unity. We used Touchdesigner to combine all the techniques we would use in the show in a single software (mapping on various video projectors, generative image, sound analysis, connection with Kinect, message management in MQTT, etc.).

To design the simulation, we used the compute shader, a parallel computing technique on the graphics card. It computes information arbitrarily and is not involved in the rendering pipeline, although it can render images. The information and properties concerning the agents were stored on texture buffers at the shader's input and output. It is a technique that uses the color information spaces of an image (texture) to store data and therefore be able to perform calculations in parallel, fast, and without relying on the computer's memory and the CPU (Central Processing Unit).

Indirect Interaction

A few types of interactions, with variable control over the system, were set up and used by team members. For example, a control interface allows the stage manager/developer to modify specific parameters concerning the virtual agents' behavior limits without intervening in their behavior directly.

During the residency, we tested the virtual system in inter-action with the performer. Her joints were detected by the Kinect camera and transposed into the virtual environment as food points position data (see Fig. 4 ). Another type of interaction was controlling the camera's position and the scene's rendering. The artistic direction employed this control to shape the virtual environment in favor of expressing the artistic intentions and sensations for the scene ambiance.

Match-Up Phases Artistic Direction

First, the virtual system developer presented the system's behavior to the artistic director. We have indicated some possibilities of exploration and visualization of the virtual environment and the possibilities of indirect interaction by experimentation with the limits of the forces and quantity of visible elements. Then, the artistic direction (A.D.) chose important moments based on observing the system in action and the various emotions and sensations that its appearance engendered. The intention was to look for movements or visual structures representing three seasons: Winter, Spring, and Fall. The director identified each selected moment's specific parameters for testing on the stage. To represent the season's energy and help refine the system, the A.D. has developed keywords to communicate her ideas:

• Winter (Fig. 5): sleeping seeds, resting, and rearranging, • Spring (Fig. 5): petals flying away, germination, and exploration • Fall (Fig. 5): dead leaves, picking, and meeting Through these keywords and key concepts, both the developer and the dancer could imagine their respective means of expression to converge toward a coherent creation -the dancer with her body, the developer with the evolving virtual ecosystem. In a previous work, our experiments indicated the importance of a shared vocabulary between the different creative spheres for corresponding to the artistic intentions with visual and behavioral aspects of the virtual generative system.

The A.D.'s exploration of configurations and behaviors of interest was fruitful for experimenting beyond the developer's expectations. We witnessed new visuals and behaviors by having another person with different expectations and ideas explore the system at the software level. From the various possibilities of rendering and behavior discovered during the experimentation of interaction between the dancer and the virtual system, the A.D. presented new ideas and directives of narration, choreography, and suggestions for exploring space. This phase of match-up amplified the horizon of sensations and concepts included in the performance.

Performer

During performative experiments between the performer and the evolving virtual ecosystem, it was interesting to observe how one modifies or influences the behavior of the other according to their progression over time. The method used to qualify and analyze the interactions promoted during our experiments was the examination of the videos of the rehearsals, the explicitation interviews, and the study of different visuals from the moments of interaction.

The representation of the performer's body in the form of the virtual agents' food points was possible only during the match-up tests. Before the match-up tests happened, in this specific research-creation residency, the performer's artistic style follows an all-encompassing principle that represents the natural order of the universe and emphasizes the importance of living in harmony with it. The practices of performer's dance are the cultivation of inner peace that originated from the sage Laozi: "The way (Tao) gave rise to the one. The one gave rise to the two. The two gave rise to the three. The three gave rise to all the ten thousand things" [? ]. With the keywords (shared vocabulary) developed by A.D., the performer absorbs, internalizes, and transforms these concepts through the inner path of the body to understand and explore the visual and luminous impressions coming from the projection.

The process of understanding and exploration of the performer demonstrates adaptation progress of freedom through perceiving the environment. The performer mentioned that her ideas of movements in this experiment are no imposed figures before the match-up tests between the two partakers(the performer and the virtual system), instead, it presents a great deal of freedom of exploring the aesthetic potential for the performer herself who can, according to the intention, speed up or slow down, move or stand still, stretch or contract, using her body to create a new representation and give free rein to the imagination.

The intention of the dancers gradually changed as the match-up tests progressed. The intention changed from paying attention to the internal energy transformation of the body, to feeling the temperature and density of the performance space, and to perceiving the behavior of different species from the virtual system. We further discovered how the system reacts to the performer's specific movements and what behaviors would be necessary for the interaction to be visible and graceful Fig. 6.

An example of co-creation during the match-up phase was adjusting the speed of the performer's movements so that the virtual agents could adapt and have time to reach the food. The dancer's movements had to be slower, and the maximum magnitude of the virtual agents had to go up to achieve a balance between responsiveness and autonomy of each virtual agent movement. This necessity was evident in the winter scene, where the camera's point of view was far away, and therefore the movements of the agents were less evident in the short term. To make them more visible, we had to increase the agents' responsiveness and maximum speed. This decision influences the selection and reproduction of the agents that will persist in the ecosystem: only the fastest agents are selected. To balance the virtual rhythm with the performer's movements, we had to slow down the performer's movements and give the agents time to reach the food, even if they were slow. The goal was to seek a more varied selection over time.

Figure 6: Different moments of the system match-up phase by the performer ©CECCI-H2M. served compelling movements of the performer towards the virtual system -signs of imitation attempt to understand reactions and immersion in the rhythm predominant in the projection. The stage manager also experimented with system parameters to make the interaction more or less apparent.

The interaction's rhythm, speed, and power were still in the research phase. The evolution process of the two interactors fluctuated according to the power of reactivity of the system concerning the performer. The variety of behaviors and viewpoints extended the scope for imagining a story or narrative that would explain the different behaviors, such as different personalities or characters of the visible agents. The heterogeneity of behaviors among the agents made it easier to have affection and empathy towards the personalities and the representation of an environment inhabited by various autonomous and unpredictable entities. The contrast highlights this variety: when we see that over time, the agents standardize their movement towards more speed and responsiveness to reach the food points more quickly.

Unlike the procedure with the artistic direction, the matchup phase carried out with the performer was much more embodied and based on her sensitive, tactile, and energetic perceptions of the scenic atmosphere created by the evolving virtual ecosystem. This intention-in-action (in contrast to prior intention) [? ? ] adapted by the performer focuses on the significant association with awareness and randomness. She is present and lives in this autonomous scenography through the improvisation practices of freedom. However, she did not consider the system's functioning, so we cannot say that being an evolving ecosystem, conceptually or technically, has influenced the quality of the interaction or the dynamics of co-creation. The dancer states that she had the impression of being in a space without gravity ("outer space"). We would like to know if we were close to embodied immersion in the virtual environment.

Initially, the variety of movement and the autonomy in the agent's decisions (the need or not to seek food, variety of attraction forces) moved the interaction away from the feeling of control and manipulation on the part of the performer. Instead, it became a feeling of immersion in an environment, in a cohabited atmosphere, where the influence between one and the other is relative and negotiable. In a retroactive dynamic, the ecosystem follows the performer, and the performer guides his movements through the rhythmic effects in his surroundings.

Stage Manager and Developer

The developer took notes and screen captures of the corresponding configurations at the specific moments that inspired the A.D. Nonetheless, the patterns depend not only on the system parameters (indirect controls) but, above all, on the interactions' history. Therefore, the variables captured by the developer only contributed partially to reproducing the moments chosen by the A.D. The vocabulary stipulated by the A.D. was the primary support for investigating the desired appearance. Guided by the keywords, the developer improvised and directed the agents to behaviors or organizations close to the metaphors expressed by the keywords. For example, if the intention was to have a warmer, agitated, and chaotic scene, the developer/stage manager sought to modify the parameters without knowing the exact consequence of such changes to seek a rendering close to expressing such keywords.

Though it was difficult to impose a specific appearance or behavior because the system was not controllable (and that was not the idea of the experiment), the developer mediated the dynamic between the A.D. and the system. To understand or predict the emergent patterns of the changed parameters associated with the interactions with the performer and the history of the millions of parallel interactions whose comprehension eludes us, we had to improvise and explore the system's possibilities in an almost striving relationship. The results of this match-up effort were sometimes disappointing for not rendering the desired appearance. However, it was often surprising to discover more satisfying visuals than expected.

We developed an interface to interact with the scenes and system variables, allowing the freedom to adjust parameters in real-time. During the presentations, this freedom was essential for taming, exploring, and discovering new movement possibilities and the virtual system's appearance. Since it is an evolving system, the parameters cannot be fixed beforehand but can only be tweaked by the stage manager during the performance. Therefore, desired aesthetic ambiances must be pursued and evolve gradually through interactions and temporal and spatial transformations of the virtual system during the performance.

Discussion

Symbiotic Imaginaries and Autonomous Individuations

The system did not count on physics simulation, and the agents did not detect collisions (despite a tendency for separation, according to the boids algorithm). Instead, the entities agglomerated, overlapped, and gave the impression of mass and fusion: as if the whole formed another element. This impression is also due to the agent's persistent alignment and paradoxical erratic manners between cohesion and repulsion. This behavior showed volumes of virtual matter moving in one direction, volumes presenting deformities and noises in their contours and shapes. From the more distant point of view, which shows the organizational phenomena on a large scale and collectively, we can see the paths formed by the agglomeration of virtual agents. The agent's trajectory features became visible through the effect of image accumulation and the reduction of their opacity. The patterns created by the endogenous interactions and their speed and direction adaptations concerning their neighbors become evident. This scene shows a less individualizing level of the agents. However, it makes visible the formation of agglomerations that resemble the formation of other individuals or at least other configured forms of a collective or a mass of agents (see Fig. 7).

The scene representing Spring is the one where the camera is closer to the agents in its scale. It reveals the entities' geometric shapes, colors, and particular behaviors. Therefore, it is a scene where the composition is more dynamic and faster, the images are beyond the control of the stage manager and the dancer, and the interaction is more mysterious depending on the area of the ecosystem focused by this point of view. Regardless, another type of empathy is produced by this scene. The dancer can differentiate each agent's life stages, birth, search for food and path, and death. That is when one understands that an association of individuals forms the previous image.

The diversity of behaviors and the multiple imaginaries inspired by the different scales of observation of the virtual system encourage us to explore performance through the evolution of interaction without having a narration or a script beforehand. The idea is constructed around and with the virtual scenography presence and by the curious exploration of its aesthetic and interactive possibilities.

While, initially, we did not have a script or description for the performance, the narrative's structure began with the virtual system's development. We manifested our imagination about a virtual performance of autonomy while constructing behavior and interactions between agents. That autonomy, in our case, is not only expressed at the virtual individual level but on the emergent collective appearances as well. It is about multiple endogenous and indirect exogenous interactions, inducing unpredictability and a sense of disobedience, resistance, or even conflict. Furthermore, the choice of losing control over the system's transformation also abstracts our intentionality. The system enacts our initial intentions and ideas, and then it is left to develop independently. Whitelaw raises these issues about the challenges of operating Artificial Life as a tool because it also carries a conceptual and cultural engagement in its expression and choices. Engagements that are narratives themselves [START_REF] Whitelaw | Metacreation: Art and Artificial Life[END_REF].

Symbiotic Creativity

Another way of seeing the emergence of new forms than the neo-Darwinist interpretation is symbiogenesis, proposed by Lynn Margulis [START_REF] Margulis | Symbiosis as a Source of Evolutionary Innovation: Speciation and Morphogenesis[END_REF]. This theory of the vital evolutionary path intersects with McCormack's vision of creative emergence through the combination of forms and behaviors. This biological approach inspires our assumptions about appropriating natural Life with technology. As Tenhaaf indicated: we take "biology as a ready-made" [START_REF] Tenhaaf | As Art Is Lifelike: Evolution, Art, and the Readymade[END_REF]. The concepts and techniques of artificial life simulation guide us toward the emergent affinity between the performer and the evolving virtual ecosystem by treating the two interactors in another ecosys-tem where we add the scene's environment. We aim for codependent relational recombination between the parts to form a conceptual and creative symbiogenesis: an association of movements, gestures, shapes, and compositions.

As explained by McCormack, the ecosystem can be more than just virtual; the user, the system, and the environment can form it. That implies the vision of the virtual system not as a tool but as a member of the scenic ecosystem. Therefore, symbiotic creation can be considered at two levels in our project, endogenous and exogenous. The endogenous symbiotic interaction exists in the association of agents when one takes advantage of the trajectory of the other to achieve its goal. On the other hand, exogenous interaction allows the organization of a symbiotic association at the level of the stage's environment. A dynamic of cohabitation between the artistic team and the virtual system is set up in a scenographic form.

Concerning the limitations and possible improvements of the virtual system, on the other hand, the task that measures the ability of agents to survive in the virtual environment is the ability to feed. This task was revealed as a not-verycreative one. Since the food is the dancer's body, the main task is to follow the dancer's body, and it was solved by selecting the most agile individuals. Nonetheless, we identified more creative tasks in the aesthetic domain: the movement and its variety and the creation of unexpected patterns. These aesthetic observations are paradoxical with the selection process we have implemented -the current dynamic values the standardization, speed, and concentration of agents on feeding themselves.

A solution would be to reverse the agents' aptitude evaluation to appreciate those not following the performer's movements as a priority. Instead, we aim to value those who prioritize the tasks of interaction and distraction in the virtual environment while keeping their need to feed themselves. These tasks that prioritize variety correspond better to the moments when rendering and behavior were more interesting.

Our new challenge is to keep a clear interaction with the dancer and choose another dynamic to enhance the variety of behaviors and value the "dancing" aspect of the agents. It is a programming approach of an aesthetic choice in the language of the rules of the ecosystem's algorithmic way of working. This translation from an aesthetic realm to a symbolic realm is our next step and our new challenge concerning metacreation and symbiotic creation.

Conclusion and Perspectives

Adding unpredictability to the stage dynamics allows the dancer to improvise and discover new movements motivated by the virtual system. Those movements are perceived by the system and modify it, establishing a creative feedback loop. The project provides us with reflections on co-creation in a symbiotic way on many levels. The stage manager performs to acquaint the system; the artistic director draws inspiration from the behavior for staging ideas, and the dancer modifies and improvises according to the perception and reactions of the system. At the internal level of the system, apparent associations between the agents form cohesive and expressive volumes.

We have put in place since last year a system to enable co-creation, which could be used as a creative partner in the process of performative dramaturgical creation (in contrast to the notion of a tool). In a metacreative approach, we have designed a machine that generates evolving patterns and graphic behaviors. The creation methodology schematized in Fig. 1 (indirect interactions during the match-up phases) is the most critical result. It makes it possible to adapt our team's system and creative process to other contexts of symbiotic metacreation for the performing arts.

Figure 1 :

 1 Figure 1: Indirect interactions between artistic team and E.V.E. ©CECCI-H2M.

Figure 2 :

 2 Figure 2: First, second and third species. The third one is represented in magenta on the right image. ©CECCI-H2M.

Figure 3 :

 3 Figure 3: General functioning of the virtual ecosystem ©CECCI-H2M.

Figure 4 :

 4 Figure 4: Performer's skeleton data translated to the E.V.E. as food position information. ©CECCI-H2M.

Figure 5 :

 5 Figure 5: Winter, Spring, and Fall represented on the performance. ©CECCI-H2M.

Figure 7 :

 7 Figure 7: Volumes formed by the agents' agglomeration, forming the impression of new virtual entities ©CECCI-H2M.

Table 1 :

 1 Correspondences between D.N.A. (R, G, B, A gene list) and virtual agent's parameters for each species

		species 1	species 2	species 3
	0 (R)	neighborhood	alignment	seek random
		turn force	force		position
						force
	1 (G)	seek target	cohesion and	seek target
		force		seek target	force
				force
	2 (B)	seek	food	separation	seek	food
		force		and	seek	force
				food force
	3 (A)	type	of	type	of	type	of
		species		species		species

Complexity Explorer -Introduction to Agent-based Modeling -Summer

2022, https://www.complexityexplorer.org 2 "arsiliath (@arsiliath) / Twitter." 2021. Twitter. Accessed October 22. https://twitter.com/arsiliath. 3 "Physarum -Sage Jenson." 2021. Accessed September 19. https://www.sagejenson.com/physarum.

Acknowledgments

This work benefited from the support of EUR ArTeC and from the funding assistance of the French government managed by the National Research Agency under the future investment program bearing the reference ANR-17-EURE-0008.

Authors Biographies

Isadora Teles is a Brazilian artist based in Paris. She is currently a Ph.D. candidate within the INREV research team at the University of Paris 8. Her artistic research and practice are in the fields of digital generative art, artistic modeling of self-organizing systems, and the design of interactive interfaces for live performances.

Chu-Yin Chen is an Artist and Professor in Digital Art, INREV research team at Paris 8 University. Her creations, based on Artificial Life and complex systems, develop interaction modes between audience and virtual creatures showing autonomous and evolving behaviors. Her digital artworks have been shown in numerous international exhibitions. Her research articulates two overlapping areas: 1] Digital Creation using algorithms of complexity and emergence, and 2] Metacognition and Elicitation of the processes of creation, enaction and aesthetic reception, via psychophenomenology and mindfulness.

Hui-Ting Hong is an experimental artist from Taipei, Taiwan. Based in Paris. She focuses on the interaction and transformation between the body, space, and mind. She aims to explore the existence and reproduction of the human body by expanding the boundaries of perception. Her researchartistic practice focuses on the perception of bodily movements and the hybrid human body, particularly discussing the virtual representation of the body and its energetic variation.