Romain Delabeye
email: romain.delabeye@isae-supmeca.fr

Olivia Penas
email: olivia.penas@isae-supmeca.fr

Régis Plateaux
email: regis.plateaux@isae-supmeca.fr

Scalable Ontology-Based V&V Process for Heterogeneous Systems and Applications

Keywords: CCS CONCEPTS, Knowledge representation and reasoning, Semantic web Verification & Validation, Ontology, Scalability, Heterogeneous Systems, Requirements Analysis

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Introduction

The main objective of the EnerMan Project (2021-2024) is to define an energy sustainability management framework in which plant data is collected and processed holistically to optimize energy sustainability. In this collaborative project, each model or approach developed by technical partners should be validated on industrial use cases. Given the geographical distance and the limited availability of the consortium's industrial systems (production systems under operation), it is usual to test scientific approaches in a laboratory environment first, with a system that is available, open, upgradeable, and easily instrumented as necessary. In this context, two key questions arise: (i) how to select a laboratory system that is representative of the industrial end-user's system with respect to a given scientific Approach To be Validated (ATV) (ii) how to verify and validate scientific approaches on heterogeneous systems (of different sizes, complexity levels, physical characteristics and operational constraints)? The case of a laboratory versus an industrial system is investigated in this paper; the question extends to heterogeneous industrial use cases though. In other words, given the scope of the project under consideration, an ambitious challenge could be: how to validate the energy sustainability of a manufacturing system with a coffee machine? To answer the first question, a unified framework is required. We therefore designed the WONKA (Verification & Validation with an ONtology and Knowledge-based Approach) framework that hosts a generic semantic representation for sharing structured knowledge from different perspectives and contexts. This framework must also support the analysis of semantic similarity and scalability between two heterogeneous systems. To tackle the second question, verification and validation (V&V) processes need to be taken into account, especially in a model-based system engineering (MBSE) context. Focusing on our case study, the developments carried out in the EnerMan project have to be applicable to a wide spectrum of manufacturing systems (automotive, food, semi-conductor, metal industries, medical devices, etc.). As a result, the corresponding scientific approaches proposed by the project partners must be generically applicable to a variety of manufacturing systems, with limited information about their architecture or behaviors. In this context, it is interesting to work on black box solutions, with only sensor data as input, which can automatically generate an identity card of the system, containing its behavior (as a model) and necessary information to estimate Energy Performance Indicators (EnPI). Therefore, the ATV for the proposed case study consists of a blind source separation method (BSS) that identifies and differentiates the operating modes of a black box system and decomposes each mode as an activation mapping of the actuators [START_REF] Delabeye | Unsupervised manufacturing process identification using non-intrusive sensors[END_REF]. This will enable to estimate and predict actuator-specific EnPI, yet we limit the scope of this case study to the preliminary pre-requisite decomposition problem. This technique has to be verified on a coffee machine (lab system) and then validated on two industrial systems, namely a heating, ventilation, and air conditioning (HVAC) system for a vehicle testbed, and a chocolate manufacturing system. The contribution of this paper consists of a methodology and software for the verification and validation of a scientific approach from a laboratory system to an industrial one, based on an ontological model. Section 2 will present state-of-the-art V&V processes, focusing on the context of scalability of heterogeneous systems, then on similarity-based approaches. Existing relevant ontologies capable of supporting the systems engineering activities addressed will be mapped. Section 3 will present the WONKA framework developed. Section 4 will detail the verification process on a laboratory system, including its selection for the next ATV validation step. Section 5 will focus on WONKA's validation process on initially identified industrial systems. Methods detailed in sections 4 and 5 are applied on the case study. Conclusions and future work are presented in Section 6.

Related Work

Scalable Verification and Validation

In systems engineering, V&V processes are used to determine whether the development products of a given activity conform to the requirements of that activity and whether the product satisfies its intended use and user needs [START_REF]IEEE Standard for System, Software, and Hardware Verification and Validation[END_REF]. Systems scalability has mostly been studied as a change in size [START_REF] Xu | Scalable validation of industrial equipment using a functional DSMS[END_REF] and design maturity [START_REF] Bailey | Address verification issues with scalable methods[END_REF], or in computer engineering applied to information systems and software focusing on their complexity degree [START_REF] Hill | What is scalability?[END_REF]. Scalability or extensibility refers more generally to the ability of a product or system to maintain its functional properties despite a change in size or certain parameters. Following this paradigm, some authors have been interested in the verification of a system when it changes its context of use [START_REF] Raji | Use Cases Modeling for Scalable Model-Checking[END_REF][START_REF] Maria | Calculating LWM2M resource semantic distance through SENACT ontology[END_REF], or during software design transformations [START_REF] Baumgartner | Scalable sequential equivalence checking across arbitrary design transformations[END_REF]. Still, scalable V&V has received little attention in the literature: some works relate to computer systems, using formal methods (e.g., model checking) [START_REF] Atoum | A Scalable Operational Framework for Requirements Validation Using Semantic and Functional Models[END_REF][START_REF] Baumgartner | Scalable sequential equivalence checking across arbitrary design transformations[END_REF]. These rarely address physical systems though, mainly focusing on simulation [START_REF] Bhatt | Towards Scalable Verification of Commercial Avionics Software[END_REF][START_REF] Groen | VECMAtk: a scalable verification, validation and uncertainty quantification toolkit for scientific simulations[END_REF]. Some authors have worked on the scalability of heterogeneous hardware systems by focusing on their sensing and actuation aspects [START_REF] Georgios | SEMIoTICS: Semantically Enhanced IoT-Enabled Intelligent Control Systems[END_REF][START_REF] Maria | Calculating LWM2M resource semantic distance through SENACT ontology[END_REF]. Still, to our knowledge, the scalability of the V&V of the same scientific approach on heterogeneous systems (with a different structure, various behaviors, and diverse missions) has not been tackled, except when considering their commonalities from a specific point of view.

Similarity-Based Approaches

To exploit the similarity between two physical entities, different approaches have been developed, depending on whether both address the same functionality, share the same behavioral model, or respect the same interaction rules. Robles et al. [START_REF] Maria | Calculating LWM2M resource semantic distance through SENACT ontology[END_REF] define that two devices are close semantically, or have a short semantic distance between them, when the devices have similar functionalities. A metamodel can be used as the backbone of the methods and process tools to be implemented to fulfill a mission or solve an engineering issue [START_REF] Long | Schema, Metamodels, and Ontologies, Oh My![END_REF]. A metamodel is then considered as a common and sharable reference model that can be used on many systems in many individual situations or configurations, provided that they similarly respect the behavior described by the metamodel [START_REF] Bénaben | A metamodel and its ontology to guide crisis characterization and its collaborative management[END_REF].

An ontology provides a unifying framework for a shared understanding between various viewpoints whatever the stakeholders' needs and their context. As a result, ontology can have the necessary depth to represent similar objects. According to the classification of Uschold and Gruninger [START_REF] Uschold | Ontologies: Principles, methods and applications[END_REF], an ontology presents four levels of formalization, of which only the formal level can support deduction mechanisms, in particular for problem solving in the systems engineering domain. Thanks to its generic representation (abstraction level), ontology is useful for the requirements definition, the automation of consistency checking and the reusability of similar concepts in multiple contexts. Some authors have used ontology to ensure verification and validation of physical systems, more specifically for security requirements related to their risk level [START_REF] Magdy Shaaban | Ontology-Based Model for Automotive Security Verification and Validation[END_REF] or their specification process [START_REF] Tsoukalas | An Ontology-based Approach for Automatic Specification, Verification, and Validation of Software Security Requirements: Preliminary Results[END_REF].

To answer the two research questions initially posed, as ontologies offer a unified framework that hosts a generic semantic representation that allows sharing structured knowledge from different points of view and contexts, they appear as an appropriate solution to support the analysis of the semantic similarity and the scalability between two heterogeneous systems.

Related Existing Ontologies

Based on the scope of the case study, we have investigated ontologies in which manufacturing systems and their dynamic behavior can be accurately expressed, while supporting V&V processes. Regarding the energy sustainability, multiple ontologies focus on energy evaluation and management in manufacturing [START_REF] Cuenca | A Unified Semantic Ontology for Energy Management Applications[END_REF][START_REF] Wicaksono | Energy Efficiency Evaluation in Manufacturing Through an Ontology-Represented Knowledge Base[END_REF], product lifecycle management [START_REF] Borsato | Bridging the gap between product lifecycle management and sustainability in manufacturing through ontology building[END_REF] or manufacturing factory sustainability [START_REF] Gagliardo | An Ontology-based Framework for Sustainable Factories[END_REF][START_REF] Giovannini | Ontology-based system for supporting manufacturing sustainability[END_REF]. Ontologies allowing for representing dynamic systems include control [START_REF] Georgios | SEMIoTICS: Semantically Enhanced IoT-Enabled Intelligent Control Systems[END_REF], condition monitoring [START_REF] Baader | Ontology-Based Monitoring of Dynamic Systems[END_REF][START_REF] Cao | Ontologies for Manufacturing Process Modeling: A Survey[END_REF] and prognostic [START_REF] Lira | OntoProg: An ontology-based model for implementing Prognostics Health Management in mechanical machines[END_REF] aspects, and aim to describe and use the interactions between related sensors [START_REF] Compton | The SSN ontology of the W3C semantic sensor network incubator group[END_REF] and actuators. The ONTO-PDM [START_REF] Panetto | ONTO-PDM: Product-driven ONTOlogy for Product Data Management interoperability within manufacturing process environment[END_REF] ontology uses a product-centric interoperability architecture including business, engineering, and manufacturing aspects. Numerous manufacturing-related ontologies, such as MASON [START_REF] Severin Lemaignan | MASON: A proposal for an ontology of manufacturing domain[END_REF] or ExtruONT [START_REF] Víctor | ExtruOnt: An ontology for describing a type of manufacturing machine for Industry 4.0 systems[END_REF], rather focus on the latter, thus allowing for a detailed expression of production operations, systems, resources and plant layout. These ontologies put the emphasis on production management, and not on the physical behavior of a plant's constitutive elements. In fact, many of these manufacturing ontologies are aligned with a sensorcentric one, namely the Sensor, Observation, Sample and Actuator (SOSA) ontology [START_REF] Janowicz | SOSA: A lightweight ontology for sensors, observations, samples, and actuators[END_REF] or one of its extensions such as SSN and DUL [START_REF] Haller | The Modular SSN Ontology: A Joint W3C and OGC Standard Specifying the Semantics of Sensors, Observations, Sampling, and Actuation[END_REF]. Together with the SAREF module SAREF4INMA [START_REF] De Roode | SAREF4INMA: A SAREF extension for the industry and manufacturing domain[END_REF], these ontologies accurately describe the physical interactions between manufacturing entities. Kesadri et al. have proposed a Verification and Validation Ontology (VVO), based on the hierarchy of viewpoints and formalisms concepts, and especially V&V techniques, in order to identify the V&V tools that comply with a V&V technique, based on a given formalism [START_REF] Kezadri | First steps toward a Verification and Validation Ontology[END_REF]. The suitable ontology required for our scope will be determined depending on the objective and context determined by the use cases.

The WONKA Framework

The WONKA framework consists of a generic semantic representation designed to formally represent heterogeneous systems and applications, from different perspectives and contexts. This framework was tailored to the V&V processes presented in Figure 1, stemming from the following problem analysis. These processes will be applied to the WONKA case studies.

Problem Analysis

V&V processes are part of Systems Engineering processes [START_REF]IEEE Standard for System, Software, and Hardware Verification and Validation[END_REF]23] and are based on requirements. As a result, it will be important to consider them in our approach. In parallel, V&V processes can be performed either by physical (test bench) or virtual experiments (simulation, analytical resolution). Some verifications can be automated by formal techniques applied to static requirements (model checking, etc.) or with simulation for dynamic requirements [START_REF] Farrell | Automated continuous verification for numerical simulation[END_REF]. In most cases, the experiments are carried out on a laboratory system, a simulator or prototype, as the real system of interest is more constrained (availability, configurability, upgradeability, etc.). Still, when developing a scientific approach to meet an industrial challenge, the choice of a representative laboratory system onto which the approach will be verified is a crucial issue for researchers. This aspect raises the question of the adequacy of an application case with respect to the intended approach to be validated. Then, validation must eventually be performed on the industrial system in its environment. This boils down to evaluating whether an approach that has been verified on a laboratory system in a specific environmentcould be successfully scaled up on the industrial system and its more constrained environment.

Approach Overview

The proposed WONKA framework addresses two main objectives: (i) to support the choice of a laboratory system that can verify a given ATV while being representative enough of the industrial end-user system, (ii) on which the ATV has to be then validated within its application environment. WONKA includes a methodology based on four main steps: (i) MBSE analysis, (ii) ontology design, (iii) requirement-based query definition, and finally (iv) static and dynamic V&V processes. First, the industrial challenge (i.e. the issue to be tackled by the industrial system in its environment) has to be analyzed in relation to an ATV, based on systems engineering principles. This requirements elicitation activity is supported by MBSE methods [START_REF] Mhenni | A SysML-based methodology for mechatronic systems architectural design[END_REF][START_REF] Ryan | Application of MBSE to requirements engineering-Research challenges[END_REF]. It aims to define the requirements that will have to be verified or validated during the static and dynamic V&V processes. For the second step, requirements will help the design or selection of an ontology able to capture all relevant aspects of the use cases addressed, including the industrial system(s) (IndSys) and the laboratory system(s) (LabSys). Third, these requirementsbuilt from the ATV, the industrial challenge, the IndSys and LabSys constraintshave to be transformed into queries based on the ontological concepts and properties, in order to be formally evaluated on the resulting knowledge graph (once the corresponding concepts and properties have been instantiated). Finally, the queries let the user know about the specific instances that satisfy or contradict a requirement during the V&V processes. If a requirement is not met, this mechanism can also provide recommendations. In this respect, recommended possible actions to take include (i) limiting the extent to which the ATV is valid by refining or adding some requirements, or as a last resort modify the ATV, or (ii) improving the similarity between both kinds of systems, e.g., by modifying the LabSys or by suggesting changes to the industrial case (e.g., adding some sensors). This process is strongly supported by both the reasoning mechanism and the expressiveness of the querying language. Requirement fulfillment metrics are finally proposed, in order to assess the scalability of the ATV (for the V&V scope) from the LabSys to the IndSys considered. The steps of the WONKA V&V processes of the ATV are presented in Figure 1.

WONKA Case Study Description

The case study onto which this V&V methodology has been applied comprises a laboratory system, i.e. LabSys (coffee machine) and two industrial manufacturing systems, i.e. IndSys (HVAC and food manufacturing production line). The operating modes identification approach (BSS technique) to be validated, i.e. ATV, consists in a two-step process: using only a sensororiginated multivariate time series, the experiment should (i) use clustering to provide a sequence of the distinct system operating modes; the algorithm then (ii) decomposes the sequence of identified operating modes into a sequence of actuators activated during these operating modes (i.e., providing the actuators' activation states over time). The laboratory use case consists of an automatic coffee machine with ground and bean coffee, made up of a pump, a heating coil, and a motor (to grind the beans). This LabSys was initially chosen for its compactness and the numerous energy transfers it contains. It was additionally instrumented with accelerometers, and later with current sensors. The first IndSys is an industrial HVAC that regulates the temperature, humidity and air flow within a vehicle testbed. The actuators are divided in two groups: a heating coil, a cooling coil, a dehumidifier, and a fan which regulate the air properties arriving to the testbed; the air is then further cooled down and humidified inside the chamber. We restrict this study to the thermal perspective, where the actuators are mounted in series and controlled according to two temperature sensors. The second IndSys considered is a mixing, refining and conching production line, as part of a chocolate factory. Only one machine with multiple tasks is considered for the purpose of this study. Three current sensors measure the machine's electricity consumption on all three phases supplying it. The three use cases, i.e., the LabSys and the two IndSys, are heterogeneous in terms of energy domains at play, actuator architectures, and missions. Their interaction with their environment also differs. This intrinsic heterogeneity will be quantitatively evaluated during the WONKA process (as a semantic similarity between systems).

Laboratory System Selection and Augmentation Through ATV Verification

In order for the WONKA methodology to be effective (i.e., to cope with industrial system unavailability and limit experimentation costs), a laboratory system is selected and augmented according to three crucial steps, as per Figure 1. That is, the ontology is fine-tuned so as to represent all systems and translate requirements into compatible queries. Intrinsic scalability can thus be evaluated using semantic similarity metrics between laboratory and industrial systems. The static and dynamic verification steps assess a system's compliance with the requirements. Laboratory systems can be augmented so as to increase similarity and verification performance.

Needs Analysis

All requirements are determined using a traditional MBSE analysis, whether these concern the ATV, the systems themselves, their respective environments, or test scenarios. Each system with its environment can have its own set of requirements (constraints), independently from the ATV. Keeping all requirements in the final representation is important, especially when there exists cross-requirements or in the event of a disturbing effect of the ATV on the system. Then a set of requirements is selected in order to express how the ATV can be considered as verified or validated regarding the industrial issue addressed.

An MBSE method is used to elicit all ATV-related requirements.

Regarding the application case study, we perform the black box analysis of the SE-READ (System Engineering based Requirements Elicitation & Architecture Design) methodology [START_REF] Mhenni | A SysML-based methodology for mechatronic systems architectural design[END_REF]. We define the requirements the studied systems (LabSys and IndSys) have to fulfill to verify and then to validate the ATV. This methodology adopts an external point of view of the system of interest (SoI), i.e. here the ATV. This black box analysis supports the emergence of a comprehensive and consistent set of requirements. Based on different views, with potential iterations between them, this aims to answers the question: "what should my system do and with which external actors/systems?". The case study focuses on the BSS ATV that meets the industrial issue of identifying the energy consumption of manufacturing systems regarding their operating modes (and their corresponding activated actuators) in an unsupervised way. It also considers the two industrial use cases (HVAC and chocolate production line).

Based on these considerations, the first SE-READ view defines the requirement related to the main mission of the SoI, i.e the ATV's mission: "The ATV is a blind source separation method that shall identify and differentiate the operating modes of a black box system and decompose them in active actuators". Then, the context view presents the SoI interactions with external systems and actors. In our case, this view allows to derive requirements from each IndSys and its environment, as external interactors of the BSS ATV. For example, an IndSys-derived requirement for this ATV is "Any disturbance of the environment shall be measured". Similarly, for the HVAC IndSys, these contextderived requirements relate to the HVAC capabilities. The HVAC system has to monitor and control the thermal environment within a specific temperature range, thus achieving the vehicle testbed's mission. The "Services provided by the SoI" view describes the different BSS ATV objectives, in relation with the ATV mission. This view allows to deduce some requirements inherent to the ATV. The final "Functional scenarios" view of the SE-READ black box analysis provides the requirements related to the description of the test sequences for experiments that have to verify dynamic requirements. An extract of this MBSE analysis is summarized in Figure 2, where the LabSys (on the left) and the IndSys (on the right) both have to satisfy the ATV requirements, within the WONKA framework.

In order to qualitatively and quantitatively measure ATV requirements fulfillment, and identify precisely the elements that do not satisfy such requirements (leading to some recommendations), we have to convert these requirements into questions. These questions will later be formalized into queries, to be supported by the ontological reasoning process. For the illustration, some selected requirements (in pink) have been translated into questions and presented in Table 1. This represents only a subset of the requirements to be validated on all use cases (LabSys & IndSys in their environment). For each actuator within a system of interest, is there at least one sensor monitoring an observable property this actuator affects? Req 2.9 (static)

In a sensor energy domain, are the actuatororiginated signals coupled with one another? (i.e., actuators in series association) Req 4.

(static)

What are the elements of the environment that may tamper with the results of the ATV? Table 1: Some selected requirements expressed as questions for querying the knowledge graph.

Ontology

Design and Requirements Formalization

Ontology design for describing the ATV and the use cases.

An ontology is a specification of a conceptualization [START_REF] Thomas | Toward Principles for the Design of Ontologies Used for Knowledge Sharing[END_REF]. It models knowledge as a collection of primary concepts and relationships between them, namely classes, object, and data properties in Web Ontology Language (OWL). Two main techniques are generally used to build an ontology: alignment to existing ontologies or appropriate ontology specification. Once the ontology is built, the systems and applications of interest can be formally represented. The instances (individuals), including their properties and values, must therefore be collected, and their relationships between one another be declared. These axioms form the knowledge base (KB). Ideally, such an ontology should be generic-enough to fit any system or application. Due to the difficulty of perfectly designing a domain ontology for heterogeneous systems (by opposition to task and application ontologies), enhancing its design after each iteration of the proposed methodology is preferred. Indeed, in research activities, phenomena are often better understood after series of experiments. Expressivity can also be increased by concept specialization. The use cases (systems and their environments) are then instantiated accordingly. As the ATV has to be applicable to both kinds of systems, laboratory and industrial, a single ATV instance will be used for both. The methodology presented in this paper was implemented on an ontology inherited from SAREF and SAREF4INMA, deemed lightweight and sufficient for the purpose of this study. This framework allows to represent both industrial use cases and less conventional cyber-physical systems in laboratory environments. A typical implementation scheme is presented in Figure 3 as an RDF graph. This ontology was designed in Protégé [START_REF] Musen | The Protégé Project: A Look Back and a Look Forward[END_REF]. A platform, be it a laboratory or a plant/industrial system, consists of a system of interest (consistsOfSystemOfInterest), an environment with miscellaneous features (consistsOfEnvironment), and possibly additional pieces of equipment (consistsOfAdditionalSystem). These relations are sub-properties of the consistsOf object property. This differentiation eases requirements formalization. Each Device or FeatureOfInterest relates to a Property, through hasProperty, controlsProperty or measuresProperty relationships. The properties themselves can relate to each other (consistsOf). This accounts for potential couplings in the systems' dynamics and the signals they originate (controlsProperty) or measure (measuresProperty). The system of interest serves a purpose through a dedicated scenario (Task). The ATV considered here, defined in our ontology as a subclass of a Task, uses exclusively sensor data. Hence every Sensor available accomplishes the ATV, i.e., provides input data to the ATV. The scenario and the ATV share an Output which may relate to a specific Requirement. In this context, an experiment's output consists of estimation accuracies (Req 2.1 and Req 2.2 respectively). Each of these requirements holds a validation threshold. Alternatively, this parameter can be held by the corresponding query. The performance of the process identification technique (operation and actuator-wise) can thus be evaluated. This output will therefore require an experiment to be computed. In order to compare each output to its corresponding requirement, they both relate to each other through the symmetric object property sameSettingAs, taken from the SSN ontology [START_REF] Haller | The Modular SSN Ontology: A Joint W3C and OGC Standard Specifying the Semantics of Sensors, Observations, Sampling, and Actuation[END_REF]. In general, should there be collections of instances of the same concepts but representing different aspects, they can be distinguished inside SPARQL queries using this object property. Overall, the knowledge base is composed of all three test cases; the ATV is uniquely defined and shared among them. Only slight modifications were made to the SAREF ontology. The object properties hasProperty and consistsOf were made transitive. The domain of the former was also extended to the Device class. Relationships measuresProperty and controlsProperty were set as sub-properties of hasProperty. Thanks to these changes, all couplings between observable properties can be revealed after reasoning and associated to specific devices. As an example, in the HVAC use case, despite the presence of five actuators between the outside temperature and the temperature measured by the first sensor, query Req 4.3 is capable of detecting an effect of the environment on the ATV (the actuator-originated properties act as proxys in this case). Inference is finally performed using the HermitT reasoner [START_REF] Glimm | HermiT: An OWL 2 Reasoner[END_REF].

Requirements formalization into queries.

We distinguish two types of requirements. The static ones depend only on use case definition (system architecture, environment, tasks, etc.), whereas the dynamic requirements must be evaluated through experiments. The requirements must be formatted in an ontological format, i.e., as a formal statement, in order to be checked by the querying engine during the V&V process. The Resource Description Framework (RDF) is therefore used. The requirements are more specifically translated into queries using the Simple Protocol And RDF Query Language (SPARQL). Not only should the requirements have a SPARQL query selecting the elements that will satisfy them; they should also include a query for the nonvalidating elements. To avoid any loss of genericity, requirements formalization is restricted to the domain ontology, i.e., the queries should not contain specializations of the core concepts, so as to be applicable to all use cases. For this reason, WONKA forces the user to conceptualize the validation criteria and better capture the limits of the ATV. Once the ontology has been designed, each requirement is formally expressed as a SPARQL query. Such a query can be parsed and visually represented as an RDF graph, as illustrated in Figure 4 with Req 4.3. This requirement seeks the individuals (environment features) that may cause the ATV to fail or underperform. In the WONKA framework, this requirement is expressed as follows: a platform (use case) consists of an entity including the environment (e.g., weather) and a device (e.g., sensor)accomplishing the ATV -, each having a property (e.g., outside and sensed temperatures respectively). The property of the device must not consist of (i.e., be affected by) that of the environment. Using parent concepts (e.g., using Device and FeatureOfInterest concepts instead of TemperatureSensor and Weather, the latter being subclasses of the former) allows to cover most interactions between a system and its environment. The ontology acts as a semantic embedding: in addition to making the (formally defined) requirements evaluable for all use cases, the solutions found by WONKA can have different meanings depending on the use case. For instance, the vehicle (acting as a temperature disturbance in the testbed) and the coffee machine's power supply are both subclasses of FeatureOfInterest in the upper ontology (SAREF, essentially), despite having very different natures.

Laboratory System Analysis and Selection

Once the ontology is designed, the knowledge graph and the queries are established, our procedure considers three activities in order to select a LabSys that verifies the ATV: (i) assess the extent to which each laboratory system is representative of the industrial ones, (ii) augment the laboratory system so as to increase verification indicators, (iii) verify the ATV on the selected laboratory system, based on the industrial use case requirements.

System analysis and intrinsic scalability evaluation.

Before launching expensive or time-consuming experiments, candidate laboratory systems can be prioritized using their intrinsic scalability. A scale factor and a similarity index between a LabSys and an IndSys are therefore computed. This scalability is intrinsic in that use cases are compared semantically, leaving out their connections to the ATV considered and related requirements. First, the respective subgraphs of the use cases are extracted from the knowledge graph. Every element of a use case originates from a single platform (a Building or one of its subclasses, as shown in Figure 3), and use cases are connected solely via the ATV. Subgraph extraction is thus straightforward. Let 𝐿𝑎𝑏 and 𝐼𝑛𝑑 be the sets of individuals in the LabSys and IndSys respectively. A simple scale factor is given as the ratio of 𝐿𝑎𝑏's cardinality to 𝐼𝑛𝑑's. Similarly to [START_REF] Mihalcea | Corpus-based and Knowledge-based Measures of Text Semantic Similarity[END_REF], we propose the following (symmetric) similarity metric between two sets of individuals.

𝑠𝑖𝑚(𝐿𝑎𝑏, 𝐼𝑛𝑑) =

where |. | is the cardinality operator, 𝑤 𝑙𝑎𝑏 and 𝑤 𝑖𝑛𝑑 are individuals. 𝑚𝑎𝑥𝑆𝑖𝑚 denotes the highest similarity index between the class of the first term and each distinct class represented in the set of individuals in the second term. There exist multiple metrics tailored to assess the similarity between two concepts [START_REF] Ali | Ontology-based approach for measuring semantic similarity[END_REF]. Any of these can be used, yet care must be taken that the two concepts considered refer to different knowledge subgraphs (despite belonging to the same ontology). The semantic similarity metric introduced by Lin in [START_REF] Li | An Information-Theoretic Definition of Similarity[END_REF] was adapted as:

𝑠𝑖𝑚 𝑙𝑖𝑛 (𝑐 1 , 𝑐 2 ) = 𝐼𝐶 𝐾𝐺1 (𝐿𝐶𝑆(𝑐 1 ,𝑐 2 ))+𝐼𝐶 𝐾𝐺2 (𝐿𝐶𝑆(𝑐 1 ,𝑐 2 )) 𝐼𝐶 𝐾𝐺1 (𝑐 1 )+𝐼𝐶 𝐾𝐺2 (𝑐 2 ) (2)
where the least common subsumer (LCS) is the most specific common ancestor to a pair of concepts, and 𝐼𝐶 𝐾𝐺 denotes the information content (IC) [START_REF] Li | An Information-Theoretic Definition of Similarity[END_REF] computed within a knowledge graph 𝐾𝐺 . In this context, 𝐾𝐺1 and 𝐾𝐺2 refer to the knowledge subgraphs of the LabSys and the IndSys respectively. Alternatively, edge-based similarity metrics can account for relationships, and thus evaluate to what extent components are similarly interconnected. Originally, three laboratory systems were considered: a 6-axis robotic arm, a 3-axis Fused Deposition Modelling (FDM) 3D printer, and an automatic bean-to-cup coffee machine.

Due to page restrictions, these systems are not presented here, yet their scalability (scale factor 𝑟 ) and similarity metrics are summarized in Table 2. The systems are represented in the same ontology, consistently with the ATV considered. This explains the high similarities observed in the plane of analysis. It is worth noting that actuators and physical properties total up to 50% of the instances of a system. Similar energy domains and actuators thus result in greater similarities. Interestingly, the coffee machine (augmented as per section 4.3.2) is the best candidate at this stage. 4.3.2 Laboratory system augmentation. The ATV, LabSys or IndSys can be adapted according to WONKA recommendations. Indeed, the querying mechanism considered in this paper allows to pinpoint specific instances unable to meet a requirement. Suitable additions according to these abstract recommendations include supplementary components or relationships. For instance, changing a sensor's location may allow it to monitor another machine. This will result in better verification performance and may increase the scalability index. Laboratory system augmentation can be performed iteratively by updating the knowledge base and assessing scalability and verification performances.

LabSys IndSys

Robotic

The recommendation mechanism is illustrated in Figure 5. The validating query of Req 2.7, ensuring that all actuators can be monitored by a sensor, is instantiated. WONKA indicates that no sensor, observed property nor actuator-induced property were able to fulfill this requirement. Nodes ?sensor, ?sensprop, ?actprop denote variables. From the query, their respective class is known. The resulting recommendation is to add a sensor within the laboratory, measuring an observable property induced by an actuatable property of the heating coil.

Laboratory system selection based on verification.

This step addresses the need to identify a LabSys that fulfills static and dynamic requirements related to the proposed ATV. Once the knowledge graph is deemed complete, queries can be applied.

Based on the results of these queries, the degree of verification or validation is simply given as the ratio of the number of verified requirements to the total number of requirements. It is also possible to use the number of combinations of individuals (i.e., each row in the SPARQL query results) satisfying the requirements over the total number of combinations of individuals concerned by those requirements. Both indicators are useful to the analysis. The former weighs the requirements equally. This verification status indicates whether the ATV will be verified on a use case. Whereas the latter allows to pinpoint the most unsuccessfully verified requirements and analyze them in more detail.

The degree of verification is first computed with respect to static requirements. The LabSys achieving the highest score is selected to conduct experiments. As experiments are conducted (i.e., the realization of a scenario), additional constraints may arise, suggesting to complete the ATV requirements. This makes the verification process more robust and reliable. These constraints can be incorporated to the set of static or dynamic requirements.

The degree of verification with respect to the ATV dynamic requirements is then evaluated.

In the example developed in the case study, a new requirement on the noise level of the sensors arose from LabSys experiments, as the BSS algorithm proved unsuccessful when using low-cost sensors.

Initially, we considered only the requirements Req 3.15, 2.9, and 4.3, as described in section 4.1 and in line with the needs of the ATV. Req 3.15 relates to system capability. The constraints Req 2.9 and 4.3 stem from an analysis of the source separation technique being used in the ATV. Clustering is performed to separate distinct operations; a subset of the centroids is selected to form a basis onto which all centroids are projected. Consequently, coupled dynamics between actuators is undesirable (Req 2.9), as the would no longer represent the true actuator combinations. No to moderate influence of the environment (Req 4.3) is also necessary to prevent environmental phenomena from being detected as actuators in this BSS problem (i.e., actuators identification). Accelerometers being non-intrusive and widely used in industrial applications, we first equipped the coffee machine with such sensors upon WONKA recommendations. As the static requirements had been fulfilled for the LabSys, an experiment was run upon the LabSys. This experiment consists in recording sensor data while making a coffee. As a result of this experiment, the dynamic requirements Req 2.1 and Req 2.2 were not met, due to the lack of vibrations the heating operation emits. The set of requirements was hence completed with the addition of Req 2.7. Consequently, the LabSys was equipped with a current sensor located on the power supply. Another experiment then proved successful. The knowledge base was updated accordingly. At this stage, all the requirements considered have been met, thus verifying the ATV on the LabSys.

For conciseness, the verification process on the laboratory system is summarized in an activity diagram in SysML in Figure 6.

Figure 6: The verification process in WONKA.

Validation of the Scientific Approach

At this stage, there exist a LabSys onto which the ATV is verified, both statically and dynamically. Though the verification process, the ATV was further specified. Some queries are soft constraints rather than strict requirements. The resulting set of requirements and associated queries is used to validate the ATV on the industrial use cases. Applying the static queries to the industrial systems allows to anticipate the extent to which the ATV is likely to be validated on an IndSys. The V&V performance metrics defined in section 4.3.3 are computed. Depending on the nature of the results, IndSys augmentation may be necessary. Furthermore, unforeseen constraints or limits may arise, leading to a partial redesign of the ATV. In particular, when some queries related to dynamic requirements are not verified by the ATV on the studied systems, the framework will recommend to update ATV. On the case study, all requirements on the LabSys were completely verified. Yet the application of the ATV onto the two IndSys could not even pass the static requirements. A lightweight requirement analyzer was developed with a view to locate individuals and object properties that do not meet the requirements, i.e., missing relationships or erroneous ones. This analysis algorithm uses Owlready2 [START_REF] Lamy | Owlready: Ontology-oriented programming in Python with automatic classification and high level constructs for biomedical ontologies[END_REF] for knowledge base manipulation and RDFLib1 for parsing the SPARQL queries. The validity of an edge within the knowledge graph, or its undesired absence, is obtained by comparing the validating and nonvalidating requirements-related queries. Their RDF graphs are instantiated, and the result is fed into the complete knowledge graph. Overall, instances and relationships that meet the requirement are colored differently than missing or incorrect elements, the latter having a higher priority. This visual aid eases the comparison between use cases in the ontology plane, from an abstract perspective.

At last, using the validation metrics earlier defined, the chocolate factory use case shows a 75% validation rate (96% in terms of validating combinations of instances) on the static requirements, against 50% for the vehicle testbed (68% in terms of validating combinations of instances). This is consistent with the results observed during the experiments on both IndSys: the ATV performed better on the chocolate factory than it did on the testbed. Thanks to these metrics, we were able to easily determine the problematic requirements and components for validating the ATV on the industrial systems under consideration. Actuators' dynamics appearing as coupled from a sensor's perspective is the primary cause of ATV failure when applied to a use case. This occurs multiple times in the HVAC use case, where the actuators are in series association. This prevents the ATV from dissociating them correctly. The second plausible cause is the effect of the environment on the ATV, as both the chocolate manufacturing machine and the HVAC are affected by external disturbances (room temperature and outside air temperature respectively). In the chocolate factory, room temperature influences the chocolate's viscosity which leads to a disturbed load torque and current consumption. However, as anticipated with the validation of most requirements, the ATV correctly identified the operations and actuators in an unsupervised fashion.

The validation process has been summarized in an activity diagram in SysML in Figure 7.

Conclusions

In this paper, the WONKA framework was proposed, together with a generic V&V process, supporting MBSE activities, for prevalidating a scientific approach on a laboratory system before being applied to an industrial use case. By formally describing systems, applications, and V&V concepts (the requirements in particular), this methodology thus enables scalability assessment between heterogeneous systems.

This methodology was applied to the abovementioned case study.

The study showed the BSS algorithm considered turns out not to be applicable to HVAC use cases due to unforeseen limits. The ATV was successfully verified on the coffee machine (instrumented with a current sensor) and validated (to some extent) on the chocolate factory use case. Future work will primarily focus on better assessing this scalability. In particular, the use of density and topology metrics will be investigated, so as to locate and evaluate structural differences and similarities between systems and proposed solutions.

The proposed methodology was mainly developed in an effort to cope with system unavailability. The WONKA framework will include cost and time effectiveness aspects, both with respect to the experiments necessary to the dynamic V&V and system upgrade (LabSys or IndSys augmentation).

The perimeter of WONKA will also be extended to the human factor. Indeed, this study was limited to physical components and systems (hardware or software). The future modules (e.g., similarly to the FBS [START_REF] Dantan | Human factors integration in manufacturing systems design using function-behavior-structure framework and behaviour simulations[END_REF] or DUL [START_REF] Haller | The Modular SSN Ontology: A Joint W3C and OGC Standard Specifying the Semantics of Sensors, Observations, Sampling, and Actuation[END_REF] ontologies) of the WONKA ontology will need to tackle the impact of the recommended infrastructure modifications (addition of sensors, etc.) on operators, associated skills, maintenance, and any nonphysical modifications.

Figure 1 :

 1 Figure 1: The WONKA framework for an ATV V&V process.

Figure 2

 2 Figure 2: Requirements (extract) resulting from the MBSE analysis. Requirement Related question for query Req 3.15 (static) Does each sensor have a sampling rate at least twice the maximum frequency of the signals the actuators it monitors can produce? Req 2.1 (dynamic) Does the ATV accurately estimate the sequence of operating modes, given a performance threshold? Req 2.2 (dynamic) Does the ATV accurately identify the actuators activated in each operating mode? Req 2.7 (static)

Figure 3 :

 3 Figure 3: Implementation scheme of the knowledge base.

Figure 4 :

 4 Figure 4: Requirement Req 4.3 represented as an RDF graph (in red, the relationship must not exist).

Figure 5 :

 5 Figure 5: Instantiated query (Req 2.7) with modification proposals to validate the corresponding requirement (green is valid, red is missing, not instantiated and to be added).

Figure 7 :

 7 Figure 7: The validation process in WONKA.

Table 2 : Intrinsic scalability of different LabSys applied to the case studies.

 2

			3D printer	Coffee
		arm		machine
	Vehicle testbed	𝑟 = 1: 1.35 81.2%	𝑟 = 1: 1.35 81.1%	𝑟 = 1: 1.40 83.4%
	Chocolate factory	𝑟 = 1: 1.31 83.2%	𝑟 = 1: 1.31 97.0%	𝑟 = 1: 1.36 98.2%

https://github.com/RDFLib

ACKNOWLEDGMENTS

EnerMan has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 958478.


Go By], has been popular for the past ten years. I'm thinking of Ivan Jablonka and his recent book, Laetitia (Paris, Seuil, 2016)

ANNE-LAURE RIGEADE:

The nature of these lives gives the impression that we are reading a novel, or rather several traditional novels. The Mata Hari section, for example, reads like a spy novel.

ANNE-JAMES CHATON: I ' y u ' also because these women had extraordinary lives that they are icons: Mata Hari had an unusual fate; Camille Claudel, too, had a terrible and sublime life. So this effect of fiction you're talking about is always generated by my very factual prose: I just transcribe the facts, which seem to be fictional because they are extraordinary. It is true that at certain points, for Mata Hari for example, we almost seem to be in a detective novel, but it's simply because I looked at police reports from the time that describe three days when she was followed in Paris; the detective who followed her wrote down all her movements and the times. I just render the document as precisely as it created a political tunnel, with the same types of actions repeating themselves. I had to cut much of it. So, I have some issues with storytelling in spite of everything. control again when I have to transition between periods of time, but ' y moments of the story that my voice is again the dominant one. Thanks to the form I chose, and thanks to my rhythm and this infusion of material (interviews, works, biographies), my voice could be absent.

ANNE-LAURE

ANNE-LAURE RIGEADE:

There is one last aspect I would like to bring up: your text is not simply a voyage through the lives of these icons of the twentieth century; it also presents a collective dimension, insofar as it offers a passage through history. You inscribe these life trajectories in eras that give your chapters their titles ("L uv u è ", "La grande guerre", "L ", etc. [The New Century, The Great War, The Roaring twenties]).

ANNE-JAMES CHATON: Yes, exactly. I also wanted to write a History of the twentieth century. And that is why I was looking for chapter titles recalling high-school textbooks. I have this memory of how my high-school history books divided the twentieth century into : "T N C u y", "T G W ", "T R g T ." A d I wanted to use those expressions, to inscribe them in this book as a kind of sequence. It sometimes happened that the titles echoed the m ' lives:

"L G D " [T G D ]
depicts the thirties and constitutes the background of W ' ; "L R v u xu "

[The Sexual Revolution] corresponds to the life-story of Silvia Kristel. These coincidences amused me, even if the encounters between life and history were not constructed or planned; it was chance. I was constrained by the given dates, so I could 't place a particular title anywhere I wanted.

ANNE-LAURE RIGEADE: It seems to me that this inscription of fictional biography in fictional history is linked to another constant concern in your work, which is your will to put the collective before the individual. I'm thinking, in particular, of an interview in which you insist on the primacy of writing over speaking because of the social, collective, communal which constantly pushes the reader to mine not only her memory but also books (or Wikipedia). The reader is always invited to mine her memories from school or from history books; you mentioned just now this temptation some readers experienced.

ANNE-JAMES CHATON: As I said, I had not entirely foreseen this relationship to reading.

But I think that if is the reader is led to mine her historical knowledge, it is because the reference to events ' always direct or immediately identifiable, insofar as these women are making history in a ma ' ntury. Some of them, like Mata Hari or Rosa Luxembourg, have a direct impact on world events through their actions. But for many others, the history of the world appears from a distance. It is as if it were filtered, either by their life or because their way of being in the world was indirect. This involves a different form of memory, a different relationship to events. life is more a pretext for exploring different literary genres, such as the travel narrative, the adventure novel, and the detective novel. It is also an expedition through language, an exploration of its various possibilities, which produces a kind of writing that seems at first blush to be very formal. "There is a narrative, but it is part of the same flat plane of colour as the exploration of narrative techniques.

1

  Anne-Laure Rigeade -Interview with the French writer Anne-James Chaton about Elle regarde passer les gens (2016) a/b: Auto/Biography Studies Volume 36, 2021 -Issue 1pp.11-23 In Elle regarde passer les gens (2016) [She Watches People Go By] Anne-James Chaton recycles biographical facts regarding 13 icons of the XXth century and re-purposes them: biographical elements of these 13 icons are entwined in a linear narrative, and become episodes of the story of a mysterious "she". Hence biography turns into the fantastic life of what seems to be the character of a novel. ANNE-LAURE RIGEADE: In your recent book, Elle regarde passer les gens (2016) [She Watches People Go By], as in your previous Vies des Hommes Illustres [The Lives of Great Men], published in 2011, you develop a unique form of biographical writing in which you reflect on history and the relationship between fact and fiction. The genre of historical fiction and of biofiction to which Elle regarde passer les gens belongs (2016) [She Watches People

  ANNE-JAMES CHATON: No. I also based my book on the works and personal writings of these women. I used a lot of texts produced by these women, especially The Diary of Virginia Woolf. To add to the answer I gave just now, my book begins to become a fiction from the moment I have to select facts, pages, extracts. I'm by , otherwise my book would reach a thousand pages! This is particularly true for Virginia Woolf: I had to choose the pages from the Diary that would really enrich my writing. I also had to choose certain m W ' b g ; the bibliography was enormous; my material was very rich. As a matter of fact, this creates a slight disproportion in the book: the section dedicated to Woolf is longer the others, because the period covered was longer, but also because I felt very close to Woolf. W ' Diary was significant to my project for another reason: it bears so many traces of what she hears on the radio, especially the speeches of Hitler or Mussolini, or of what she reads in the newspapers, for example the details of the Louise Maud Steel affair (p.79). And my project was to produce a portrait of the twentieth century. W ' enmeshment in her era gave me wonderful material for re-inscribing her life in her historical moment. ANNE-LAURE RIGEADE: What was your writing process like: did you read and write straight away, or leave time to forget what you had read ? With W ' Diary, for example, it seemed to me that you took whole sentences from it. and, as a matter of fact, I copied certain passages almost entirely, translating them into the subject-verb-complement form. But there was a kind of forgetting when we revised the book, my editor and I. For instance, I k Em Z ' m u "J' u ", when Camille Claudel reads the newspaper l'Aurore; the letter was ten pages long. I cut it in the end because it drowned the reader, and I only kept a few sentences from the letter. So, I made certain cuts, which were important in the sense that the manuscript I gave the editor was twice the length of the published book. This prolixity is also one of my flaws as a writer: I end up developing an obsessive relationship to these figures and their universe, since I try to capture the most everyday, the most ordinary details, and maybe as a result the most intimate ones; I seek to write what History forgets. But sometimes that puts the story out of balance and weakens its impact. I worked with an editor on the rhythm, eliminating whole chapters, whole biographies. For example, I wanted to write the life of the aviator Amelia Earhart, but I realized she talked of nothing but clouds; she was always up in the clouds, in her cockpit. The story ended up being very weak. I had to give it up. The opposite sometimes happened: my material was too rich. In the beginning, I wanted to dedicate a large part of the book to a series of female politicians; I began with Indira Gandhi and went all the way to Margaret Thatcher. I was writing these biographies, and, at one point I realized I had the same problem:

  , for example, which 2016. What is your view of these contemporary works? What is your relationship to it? Portraits is a plastic arts project that I began in 2001. It is anchored in my research in literature, sound, and the plastic arts on what I call "p g", referring to the everyday documents that we all have in common, that we constantly carry on us and with ussales receipts, racing tickets, bank withdrawal receipts, reward cards, health insurance cards, parking tickets, credit card receipts, etc.and that tell stories about us, about our lives. These documents always include intimate details, like a hand-written letter from someone close to us, a bank statement, or a prescription. Nevertheless, the subject is always But this never is my starting point; my starting point is more the still image; this is more a gallery of paintings, which I filter through the writing canvas, and which comes to life -JAMES CHATON: Yes, and that is why this book is indeed a narrative; the portraits become biographies because they relate stories that happen within a given length of time. I actually relied on a lot of biographies to write this book and I realized at that point that biographers were not always reliable. I read four or five biographies for each woman, and reconstructing the exact chronology of events took a huge amount of work because biographers are not always rigorous when they establish dates and facts. It is true that the women I've chosen had exceptional lives, and that they thus inspired romanticized biographies that strayed from the factual truth. I chose to use these biographies nevertheless; I

	ANNE-LAURE RIGEADE: As a matter of fact, you published a book called Portraits (Paris, fiction is produced by the meld g 13 v , u qu "she": the fiction would be harder to see. It is the reader who produces the fiction, or rather the level
	Al Dante, 2013). who lives for more then a hundred years can only be fictitious. This is an effect of reading, of fiction, because, in my opinion, there are several: the more he knows ' ves,
	in this way. though, because I did 't imagine just one character in the beginning, I the less he reads the book as a fiction, and the more he experiences it as a completely factual 't construct a
	' ANNE-LAURE RIGEADE: When you talk about your "writing canvas ", you' referring, I u y um m y , k k suppose, to the formal framework that guides the writing, specifically the fact that each sentence begins with " " [ ], u ying whom this pronoun is referring to. We can' y " " u ' x m y k g b b u women's single character, but really 13 distinct lives of 13 real people. I ' m m they are all woven into the same fabric that produces th u y, " ," . This means that for a reader who sees the seams, the fiction wouldn' k. When I read the book, ' k m , because I know the exact sentence that makes the transition ' m g tion can run free, ' " v " u : I imagine all these cross-fades between m ' v ; very often, the woman travels or faints, when in reality she died. biography. On the other hand, if he knows nothing about these women, he will read the book like a jumbled novel, because these w m ' v y v lesque. I wanted to create these levels of fictionality that vary from one reader to another. But what I had not anticipated is the fact that readers, as some have attested, would stop reading, or would go back to ANNE-JAMES CHATON: Yes. different, biographies. from one woman to another. As a matter of fact, this is one of the rare moments when the identify the woman I'm talking about, for example. I wanted the reading to be quick, as I said:
	receipts, bills, etc. When I begin som	'	, I k m	g v m every piece of
	ANNE-LAURE RIGEADE: We can think of the moment the text switches from Rosa
	Lux mb u g I	Du	: R	Lux mb u g'	replaced by a story of exile, a
	[Camille Claudel] fiction that you invented, that glides gently to Isadora Duncan: "Elle attend Pieck. Elle reçoit 'Ex u v 1900. Elle a achevé L'Âge mûr. Elle
	u	ux	' x	. E . E		mb	u	' u	è . E ' x . Elle retournera à Paris. Elle connaît bien la v ju y. E
	France. Elle y a vécu. Elle parle la langue. Elle passe par la frontière suisse. Elle arrive dans la
	capitale française. Elle trouve une chambre à louer dans le IXe arrondissement. Elle est en
	ANNE-JAMES CHATON : No, Nothing. My material is not at all fictional. But the richness juillet. Elle est sur les Champs-Elysées". [She waits for Pieck. She takes the road to exile. She
	ANNE-JAMES CHATON : I		' situate myself at all in relation to this work for two
	of detail transforms reality into fiction in the reading process. The effect of fiction is first will go back to Paris. She knows France very well. She lived there. She speaks the language.
	reasons: first, because I come from a literary scene that is more the poetry scene, and from a
	generated by the accumulation of facts. Second, there is the stylistic device I was talking She crosses the Swiss border. She arrives in the French capital. She finds a room to rent in the
	rather formal style of poetry known as sound poetry. So I do 't know contemporary fiction
	about: this syntax, this canvas subject-verb-complement-which was a formal constraint that 9th arrondissement. She is in July. She is on the Champs-Elysées.]
	very well: poets and novelists	' m v	m	lectual circles. Second, my starting
	I decided on in the beginning-speeds up the writing in a way that forces the reader to be
	point was really in pa	g				g. I'v	k	u .
	carried away by the rhythm of the story, just as though she were reading pure fiction, because ANNE-JAMES CHATON: Yes, that' g . For someone who knows as much as I do about
	the rhythm does not give her time to wonder about the historical reference point. Finally, R Lux mb u g' in this example, and about the lives of all of these women in general,

writing he carries with him, everything he has in his pockets, in his wallet, in his bag if he has one. I take a picture of these documents, and then transcribe it all, which makes for a very long informative text transformed into a 120 cm x 176 cm poster. This generates a text-image, very similar to the nude in photography, which is screen-printed. Portraits is more an exhibition catalogue, in some sense, gathering text-images that invite a non-linear reading by drawing on the visual rhythm of the writing.

ANNE-LAURE RIGEADE : And in

Elle regarde passer les gens (2016) [She Watches People Go By]? ANNE-JAMES CHATON: Elle regarde passer les gens (2016) [She Watches People Go By] is based on the model of the portrait more than the biography. Since I'm er, and I deal with different material, with written material, these portraits become the written record of a life. ANNE-JAMES CHATON : Yes, that' right, and also to the fact that I have chosen to write very short sentences, very quick, very simple, with a very meagre vocabulary and minimalist syntax. ANNE-LAURE RIGEADE: From this point of view, the first sentences set the tone: "Elle explique son travail aux membres de la commission. Elle est recalée. Elle est révoltée. Elle est blessée" (p.13). [She prepares the exhibit for the W ' F of 1900. She has just finished Middle Age. She wants to exhibit it. She gathers other works. She goes before the committee. She explains her work to the members. She is refused. She is outraged. She is hurt.] To come back to what you were saying about the portrait, it seems to me that these lives nevertheless have beginnings and ends: the book is punctuated by dates, starting with this very first date of 1900, and weaves a chronology just like any biography. ANNEdid ' reject them on the grounds that they had no scholarly value, but I selected only the informative, factual elements in them, and I eliminated everything that was invented. I wanted to keep them, because they are part of each of these myths, and because they attest to these myths. I did 't want to use a history book, just biographies, precisely because they build a hero or heroine, because they bear the memory of a certain moment, a certain way of looking at the icons of the time. At the same time, I wanted to be sure the facts I kept were accurate. My material is thus not at all fictional, but very well documented, very factual. ANNE-LAURE RIGEADE : So you are saying there is nothing fictional in your book? the title is also the first sentence, to indicate that the reader is supposed to read linearly and stop only at the final sentence. For what I had in mind, the reader was not supposed to go back to earlier parts.

  She is dry. She is studded with split tree trunks. She crosses a clearing. She is a young deer.She is crowned with wood. She jumps. She crushes a palm branch. She is green. She is delicate. She is deciduous. She is shot with nine arrows. She suffers. She is serene. She finishes the painting. She calls it "The Little Deer"]. In general, this happens when I'm describing images or videos; I resort to them more and more as the book goes on. The book actually follows the technological evolution of the century: I only used a few images for the first biographies; but from the fifties on, I drew a lot from photographs and films: the film of Some of these women have given rise to vast bibliographies, inspired a lot of biographies. T ' the case for Diana, or for Jackie Kennedy. So, it's more the selection of works that orients the point of view. The effect you describe comes from works I read and kept in mind: the point of view of the book is really that of the biographies I

	used. L y D	' b g			mpletely manipulative.
	ANNE-LAURE RIGEADE: I	m	m	'	g oint here: your book
	aims to produce a repertoire of twentieth-century icons. And in L y D	'	, she is
	K inscribed in collective memory-less through biographies than through magazines, whose y' , or some of y ' Sy v K ' films. These
	g ambition is maybe also to establish forms of historical truth-, as an icon of generosity. As a m m u ' m g tion because the material is no longer a text but
	result, your own portrait does '		y	' ,	v g	weakens
	our shared sense of her iconic status.
	She's not fossilized yet; she is still too mobile to be fully grasped as an icon. T ' true from
	'	v	as much	' . F	m , by contrast, they have
	fewer traits, but those traits are more significant, each functioning as synecdoche.

possible. T ' t produces fiction. ANNE-LAURE RIGEADE : I talked about "novels", u , just now because the book takes us from one genre to another: the spy novel with Mata Hari; the erotic novel with Sylvia Kristel; the psychological novel with Virginia Woolf, etc. ANNE-JAMES CHATON: This comes afterwards. When I write Mata Har ' , I ' know I'm writing a detective novel, for example. It's the effect of writing in this case. The document I use, the document I rewrite -a police report for Mata Hari, a film for Sylvia Kristel, a radio recording for Virginia Woolf, the most objective possible transcription of what you see on Zaprud ' m, .these documents themselves direct the book to different genres of fiction. I did ' to propose a voyage through different genres of novels, just to produce a list of facts, a list of sentences. Since I only record facts, and since these facts have in themselves a certain shade, this transfers into the writing. ANNE-LAURE RIGEADE: Your project is unique because the definition of biofiction relies on the very postmodern hybridization of fact and fiction, literature and history. Meanwhile you derive the fiction from the facts themselves, without altering them. It is extremely original. The fiction is thus limited to a few transitional sentences that move from one woman to another. ANNE-JAMES CHATON: Not exactly: there are moments-rare ones, bu y' where I can let my imagination run free: there are subjective moments, like in the description F K ' g : "Elle est dans une forêt. Elle est sombre. Elle est sèche. Elle est m ' b u . E le traverse une clairière. Elle est un jeune cerf. Elle est couronnée de bois. Elle bondit. Elle écrase une banche de rameaux. Elle est verte. Elle est délicate. Elle est feuillue. Elle est percée de neuf flèches. Elle souffre. Elle est sereine. Elle achève la peinture. E ' u L P C " (p.121). [She is in a forest. She is gloomy.

an image. Also, ' ue that the similarities between the women produce fiction, for example dance for Mata Hari and Isadora Duncan, or the communist thinking of Rosa Luxembourg and the fact that Frida Khalo relates her meeting with Trotsky. These moments reinforce the idea that there is only one character, the facts paradoxically give body to a fictional character.

I could give a lot of examples of such internal links in the text that push it toward fiction.

ANNE-LAURE RIGEADE: It seems to me that the subjective also intervenes in the way you look at these women, and sometimes the judgements you make about them: princess Diana, for instance, is described as a terrible manipulator when you write: "E v ' ô

Luanda. Elle prend une jeune fille dans ses bras. Elle a perdu une jambe. Elle demande à un g ' tant. Elle veut une photo choc" (p.250). [She visits the hospital of Luanda. She takes a young girl in her arms. She has lost a leg. She asks the photographer to capture the moment. She wants a shocking picture]. Did you intend in this way to offer particular points of view on these women? ANNE-JAMES CHATON: No. ANNE-JAMES CHATON: For me, this comes from the fact that Diana is not yet an icon like

Marilyn might be, because our memory of her is too fresh: Diana is too close from us; the portrait is not yet fully drawn. We accept the faults as well as the virtues of an icon; we accept her this way because she comes to us from an already remote past. But ' not the case for Diana. In 30 years, we will see her more clearly, and I'm u I would write her differently.

ANNE-LAURE RIGEADE: L ' g b k y u u es: your factual sources were biographies, but also films or photographs. Is that everything?

  and if my prose changes in colour, it's because this life or that one is characterised by Diary attests; unlike women like Marilyn or Jackie or even Isadora Duncan, who were very oriented to the outer world, Woolf experiences the world through the filter of her consciousness. Naturally this transfers to my text, not because I intervene but my narrative, from 1900 to 2000, and to setting a certain rhythm of writing, a certain speed. Those are the two things I pay attention to when I select the elements of the story. After that I can add details that link them, but t ' We are the representative of young Russia. We are not mixing in political questions. It is only the field of art that we are working. We believe the soul of Russia and the soul of America are about to understand each other. We are come to America with only one idea-to tell of the Russian conscience and to work for the She talks about America. She expresses her gratitude. She did not come to talk politics. She is only interested in art. She believes in the friendship between the two countries. She thinks these nations can understand each other. She came to the New World with one idea in mind. She' ot propagandizing. She wants to expose the Russian soul to Americans]. It really is her language, her words, her voice that you hear in my prose, but I

	ANNE-JAMES CHATON : No, not at all. I had written a masculine History, and then I wrote seule idée en tête. Elle ne fait pas de propagande. Elle v u uv 'âm usse aux
	a feminine history. The "he" history, even if she does it from the margin , volume gives way to the "she", "she" who makes "b k " k y. These women have an indirect relationship to history. Elle regarde passer les gens is the mirror image of the previous volume, even if the first one was constructed in a very different way. E " " of a great man is the result of rewriting a text or biography by a great writer of a great man, for example Suetone writing Emperor Tib u ' Lives of the Twelve Caesars. Once a certain type of action. I ' y m : I ' y m k H ' more dramatic, under the pretext that she is going to die; ' just that Mata Hari is a spy, and as a result when we read her life, we read a spy story. The same goes for Sylvia Kristel: I would never have imagined writing erotic literature; ' my favourite subjects. But I have to write erotic literature when I tell her life-story because she was an actress in erotic films, and because I describe scenes from these films. I think the same observation could be m u , ' not as necessary. I'm m the rhythm of the prose: it's almost like writing aloud. ANNE-LAURE RIGEADE: Exactly, you really make the v . I'm u m Américains." (p.60) [think this is possible only thanks to my form . W m ' v
	I had created these duos, I looked for a form of writing that would correspond to the model or made for each m : W ' r life comes through because she is very attuned from their experiences, but you manage in your writing to capture distinctive ways of again precisely because ' very simple style that limits my hold on their lives, the possible
	to the portraitist: in the case of Jules Vernes account of Christopher Columbus' voyage to America, I u Ju V ' v encoding all the place names and u geographic references in latitude and longitude that the navigators used. As for the life of Dante according to Boccaccio, I B ' x , and then translated this ' y g. speaking, and that attests to a form of ethical concern for preserving the voice without savagely appropriating the discourse. interpretations I can make, and any subjectification. This phenomenon is also linked to my model, my source-materi , b u ' v I b proper sense to her inner life, as her because I : g v v , ' v I . Sometimes, I take
	first version into " x g" gu g		were text messages, referring to the fact that Dante
	had invented the Italian language. ANNE-LAURE RIGEADE: You'v	that you only relied on a list of facts, but you give
	these women an inner life. To go back to the example of Marilyn, you write: "Elle est
	ANNE-LAURE RIGEADE: there is always a suspicion, when a male writer appropriates ubjugu . E m u u " (p.140) [She is captivated. She is in love], or: "Elle est
	m ' u u . E	g m d it with his own work, that he may be repeating a form of dominance u u " (p.145), [She is happy. She is furious] or: " m "
	traditionally exercised over women. And the reader is struck by the fact that despite an (p.156) [She is depressed]. In this sense, you seem to want to construct an inner self, like any
	apparent unity of style, due to the formal constraint you placed on yourself, one perceives novelist would.
	d'Hommes illustres recounts History from the G different voices, as if you wanted to let those voices speak which a certain patriarchal history ' point of view, Elle regarde passer
	les gens m had wanted to silence. m ' ANNE-JAMES CHATON: Yes,	v . Would you say that there were drives, desires, ways ' true. But that can be explained by the influence of the
	of doing and writing that were different depending on whether you were writing the lives of biographers I read while writing. I used a lot of first-hand accounts evoking the states of mind rapprochement of the two great countries. No politics, no propaganda !". And here is my
	women or those of men? ANNE-JAMES CHATON: I think this particularity is linked to the women themselves. These of these women. In Marilyn' case, her relatives all say that she was sad. I'm b like a transposition : " E 'Am qu . E x m g u . E ' pas venue
	parler politique. E	'	qu'à ' . E	' m	deux pays. Elle pense
	qu	uv	'	. E	v u u		u N uv u	v u

RIGEADE: I'd like to talk about the gender question. You wrote this series of biographical stories in Elle regarde passer les gens after Vies des hommes illustres. Vie different coloursbecause the prose is a bit like a rainbow of the lives of different womencome from the fact that each has her own relation to the world. I was content to establish a list of facts, sponge. It' u that I also select and keep those parts about their inner life, but I ' initially mean to create a psychology for these women. I give priority to facts that assure the chronology of ANNE-JAMES CHATON: Yes, because I also work from interviews and reported speech. I rewrote a lot of interviews. I'm k g, example, about the one Isadora Duncan gave to an American newspaper, where she shocked the press. I take I Du ' interview with The New York Herald; I transform her words into a series of sentences obeying my canvas subject-verb-complement, but they are still her words. Here is an extract of the interview that Isadora Duncan gave to the newspaper: "Here we are on American territory.

Gratitude, that is our first thought.

  As time went by, I allowed myself to treat singularity but that was never the starting point for me. For a long time, I believed that I had found a very objective style, that would have resolved the problem of subjectivity in writing, and so the problem of my own authorship, in a way. I ' because the collective comes before individual speech for me that I wrote this essay on Marx. In my early works, I worked a lot on texts generated by machines, on words nobody uses. My first book was called Evenements 99 [Events 99]: for one day, I kept all my tickets, as so many witnesses of my presence in the worlda bank receipt, a metro ticket, a shopping list, etc. Then, I transcribed all these tickets in their entirety. Afterwards, I told myself I had found an entirely objective way of writing. It goes without saying that in spite of this I had breathed something of myself into the text, since I was the one who manipulated these texts. But I was 't conscious of that at the time. Later, I realized that these texts remained a form of narrative, and that they told my story. The before becoming icons, these women are books, published biographies, works that others can buy and read. Had I not written Elle regarde passer les gens, I could have done an art installation with all the books I read, the photographs I used, the videos I watchedand this would have composed an archive. Unlike what I was doing fifteen or twenty years ago, When you quote this interview where I say that writing takes priority over speaking, it's also because the world takes precedence over the individual, it contains him or her. And to prevent the individual from erasing the world, my strategy, in a way, is to begin with the world, but to take from the world only what is most ordinary or most fossilized, only what incarnates or evokes an epoch or a moment with as much immediacy as possible. She learns of the annexation of Austria]. You keep one evocative event, but also one micro-event of everyday life, the importance of the radio. In these life-stories, you keep a lot of details of the everyday lives of these thirteen womenan appointment at the oculist, for realized ten years after having written Evénements 99 that there really was a subjective view at work behind this collection of tickets. At the same time, I spent fifteen years reading Edmund Husserl, and I think my stance comes from Husserl and Marx and the American objectivists as well as from Pérec. I'm looking for a way to be closer to my objects.Emmanuelle, released in 1974, and the Emmanuelle years covered exactly the period the book was missing. The same thing happened with Frieda Khalo: I had to add someone who would take me from the end of the war to 1954, I looked for someone, and Frieda Khalo was the one who best fulfilled the criteria. And I was very happy, because I had 't thought of her at the beginning. And writing about her enriched my writing, because it enabled me to explore a

	new dimension with the description of her paintings,	u '	v b	b
	without this, despite the influence of the visual and pictorial imaginary on my work. So, the
	chronological constraint also created happy coincidences.
	ANNE-LAURE RIGEADE: This really is striking: in a chapter where Virginia Woolf I'v allowed myself a lot of freedom with regard to this ideal for the past twenty years, until I ANNE-LAURE RIGEADE: There are 13 lives. Does the number 13 have a particular
	, "L m managed to publish a book in a publishing house for novels, Verticales, which would have m " [T R F m], a single sentence conjures the significance?
	dimension of writing. But I'm after eme 99 [Events 99], is an essay dedicated to Marx and effacement, (L' ffac , thinking of your work: one of the first texts you wrote, capitalisme et effacement dans les Manuscrits de 44 de K. Marx (2005)). Can you explain this concern with the collective in your writing, and your way of articulating singularity and community? "I," u y seemed central, as if ' b hidden till that moment. I grieved individuality becomes possible again because I rewrite my primary source-material; before, I did 't rewrite: I copied, I transcribed. ANNE-LAURE RIGEADE: Is this also why you chose to inscribe these narratives, these life-, H y "H"? year 1938: "Elle écoute la radio. E ' x 'Autriche" (p.96) [She listens to ANNE-JAMES CHATON: I have a writer m y: "I u and what y u g: y u y u P ". H completely understood what I was doing before I understood it myself. I love Georges P ' description of the Mabillon Carrefour in Te a i e d' pui eme d'u lieu pari ie [An Attempt at exhausting a place in Paris]. What m b m m P ' mu ; ' y the position of an observer, an almost mechanical recorder. In his way of writing, we sense an been unthinkable for me a few years ago. doubt. Bu I k m ' v b u I v k. However, the chronological constraint led me to exclude these women because they lived too long. For example, I had thought of Marie Curie, but her life would have covered 50 years of the century. Other choices derived from this constraint: I had already written a few lives, and I still had a few gaps in my story. I had to look for other women. After eliminating Golda Meir and Indira Gandhi, I realised I had to fill nine years betw J ' T ' ANNE-JAMES CHATON: Subj , the idea of completely disappearing from my text. But I kept going, I always sought to use, as the bedrock of all my written work, material that ' my own. In Elle regarde passer les ANNE-LAURE RIGEADE: Your book is anchored in History in a different way: you never ANNE-JAMES CHATON: N , . I ' b y, b u u g g k, bu ' g ican . I ' umb , by y: it can go up to fourteen the radio. x m , V g W , J J " S v A my here to give value and attention to the ordinary? stop playing ' m m y. For example, I would not have chosen the same thirteen women you did. How did you make that choice? ANNE-JAMES CHATON: I chose these women first because I knew their images would appear immediately before the reader, because I knew they could be identified without a lives if you include Joan of Arc, who appears in a flashback. gens, I'm coming back to a form of narrative prose that can be read linearly. Singularity, canteen" ("dépend de la 'A m u S u " -p.170). Is there P rec-like desire ANNE-LAURE RIGEADE : Y u y ' u u : this book,
	ANNE-JAMES CHATON: Yes, because the subject of the book is History itself, more than individual in the world, who tries to write it, who appropriates the world by writing it. He election as Prime minister, between 1970 and 1979. By chance, I come across the film
	the stories of these women. In a way, the " " in its 700 occurrences, is History [history talks about " m at exhausting" , u be exhausted by a single
	being a feminine noun in French]. The primary subject of the book is the twentieth century. consciousness. T ' g b links me to Pérec and drives me to try to do

something less. I'm one step behind him, in the position of the person who observes the world without having any influence on what he sees. I'm not saying I'v u , since, as I said earlier, I

  laisser seul pendant la crise. Elle est à la Maison Blanche. Elle est cloîtrée. Elle a interdiction Elle ne croit pas à la guerre" (p.162) [She is in October 20th 1962. She' just arrived at Glen Ora. She receives a call from John. She has to fly back to Washington immediately. She will be transported by an Air Force helicopter. She will be taken without delay to the nuclear shelter of Camp David. She refuses. She wants to stay with her husband. She ' leave him alone during this crisis. She's at the White House. She is confined. She is forbidden to go out. She is surrounded by secret service agents. She is calm. She keeps her nerve. She wants to lift the mood. She organises a dinner. She invites close friends and family. (…) S believe there will be a war]. ANNE-JAMES CHATON : T ' g . As you see, the event is not named: there' ju tension in the air: Jackie is asked to fly back to Washington, they even suggest that she take ug ' u . T 's what points to this major political moment that was the Bay of Pigs. It's the same with Woolf: her contact with history is indirect but constant, ever-present when she travels around Europe, for example, and sees the signs of growing anti-semitism. ANNE-LAURE RIGEADE: One last question: are you currently working on any projects that put into practice-no doubt in a different way-life writing? ANNE-JAMES CHATON: I'm currently working on the travel narrative of Jean-François La

	. E	u	' g		u . E	m . Elle garde son sang-froid. Elle
	v u	' m	è . E	g	u î . E	v	. (…)

Pérouse. The book is called L'affaire La Pérouse [T P u A

]. Bu v g '

ANNE-LAURE RIGEADE: Y ,

' m m y is drawn in these two directions you highlighted: toward rereading history, and toward a desire to identify the women.