<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Translating Requirements in Property Specification Patterns using LLMs</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Dario Guidotti</string-name>
          <email>dguidotti@uniss.it</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Laura Pandolfo</string-name>
          <email>lpandolfo@uniss.it</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Tiziana Fanni</string-name>
          <email>tiziana.fanni@abinsula.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Katiuscia Zedda</string-name>
          <email>katiuscia.zedda@abinsula.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Luca Pulina</string-name>
          <email>lpulina@uniss.it</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Abinsula Srl</institution>
          ,
          <addr-line>Viale Umberto 42, Sassari, 07100</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>University of Sassari</institution>
          ,
          <addr-line>Piazza Università 21, Sassari, 07100</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>This paper introduces ReqH, an innovative tool designed to streamline the translation of natural language requirements into Property Specification Patterns. The tool leverages the capabilities of Large Language Models, which are renowned for their ability to comprehend and generate human-like text. ReqH aims to address the challenges of translating informal requirements into formal specifications, a process that is crucial in industrial contexts, particularly within safety and security-critical domains which demand rigorous formalisation to ensure the reliability and security of systems. We present some preliminary results from evaluating our methodology on a dataset of semi-automatically generated automotive requirements. The findings indicate that Large Language Models, when applied to this translation process, show significant potential for improving the accuracy and eficiency of requirement specification.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Natural Language Processing</kwd>
        <kwd>Formal Specifications</kwd>
        <kwd>Large Language Models</kwd>
        <kwd>Property Specification Patterns</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        In industrial contexts, particularly within safety and security-critical domains, the accurate specification
of requirements is of paramount importance. Requirements serve as the foundation upon which systems
are designed, developed, and validated. In these high-stakes environments, any ambiguity or error in
requirement specification can lead to catastrophic failures, resulting in significant financial losses, harm
to human life, or severe environmental damage. Therefore, ensuring that requirements are both correctly
captured and precisely translated into formal specifications is essential for the integrity and reliability
of systems [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. Natural language remains the most common medium for expressing requirements
due to its accessibility and ease of use by domain experts. However, natural language is inherently
ambiguous and often lacks the precision required for formal verification and validation processes. In
safety and security-critical domains, formal specifications are crucial because they enable the use of
formal methods—mathematically based techniques for the rigorous specification, development, and
verification of software and hardware systems. Formal methods allow for the exhaustive verification of
system properties, ensuring that critical requirements, such as safety constraints and security protocols,
are met without errors or omissions [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. These methods have been successfully applied across various
domains, including the verification of hardware circuits [
        <xref ref-type="bibr" rid="ref4 ref5">4, 5</xref>
        ], flight control systems [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ], and increasingly
in machine learning [
        <xref ref-type="bibr" rid="ref10 ref11 ref12 ref7 ref8 ref9">7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24</xref>
        ], where they help ensure
the reliability and correctness of complex models. The translation of natural language requirements
into formal specifications, such as Property Specification Patterns (PSPs) [ 25], presents a significant
challenge. This task requires both a deep understanding of the domain-specific requirements and
expertise in formal languages, which may often be inaccessible to domain experts. As a result, the
translation process is prone to errors and ineficiencies, which can compromise the efectiveness of
formal verification. This topic was the focus of the Use Case proposed by Abinsula Srl in the scope of
the AIDOaRt project, a Key Digital Technologies Joint Undertaking (KTD JU) project started on April
2021, in which the University of Sassari participates as an Artificial Intelligence (AI)-based solutions
provider.
      </p>
      <p>To address this challenge, we introduce ReqH, a tool designed to facilitate the translation of natural
language requirements into PSP by leveraging Large Language Models (LLMs). LLMs, which have
been widely recognised for their ability to understand and generate human-like text, ofer a promising
solution to bridge the gap between natural language and formal specifications. ReqH aims to simplify
the translation process, making it more accessible to domain experts who may not be proficient in
formal languages. To evaluate the efectiveness of our proposed methodology, we collaborated with
automotive domain experts from Abinsula to develop a comprehensive dataset. This dataset comprises
1000 requirements articulated in natural language, along with their corresponding PSP versions. This
dataset serves as a crucial resource for testing and refining ReqH’s capabilities, providing a robust
foundation for assessing the tool’s performance in real-world scenarios. In addition to developing the
dataset, we employed another tool, ReqV, to automate the evaluation of the syntactic correctness of the
PSP translations produced by ReqH. ReqV systematically checks the translations against predefined
syntactic rules, thereby ofering an objective measure of the accuracy and reliability of the generated
PSPs. This automated evaluation process not only facilitates large-scale testing but also ensures that
the results are consistent and reproducible.</p>
      <p>The preliminary results from our evaluation highlight ReqH’s ability to handle a diverse range of
requirements, demonstrating its versatility across diferent types of specifications. While the tool shows
strong potential, the results also indicate areas for further enhancement, particularly in refining the
translation accuracy for more complex or ambiguous requirements. Nevertheless, these findings afirm
that ReqH has the potential to significantly reduce the manual efort required in the translation process,
ofering valuable support to domain experts who may not be familiar with formal languages.</p>
      <p>The remainder of this paper is organised as follows: Section 2 introduces some basic concepts and
definitions. Section 3 present the Abinsula Case Study from which this work originates and, more
in general, the AIDOaRt Project. Section 4 presents the methodology employed in our study and the
models and dataset considered in our experimental evaluation. Section 5 describes the experimental
setup and presents the results of our empirical analysis. Finally, in Section 6, we briefly summarise our
conclusions and highlight future research.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Background</title>
      <p>This section provides an overview of the key concepts underlying our work: Natural Language
Processing, Large Language Models, and Property Specification Patterns. These topics form the foundation for
understanding the methodology and tools developed in this paper.</p>
      <sec id="sec-2-1">
        <title>2.1. Natural Language Processing</title>
        <p>Natural Language Processing (NLP) is a crucial area of artificial intelligence that focuses on enabling
computers to understand, interpret, and generate human language. It serves as a bridge between human
communication and computer understanding, making it possible for machines to process and interact
with language in a meaningful way. NLP encompasses a wide array of tasks, including but not limited
to text analysis, sentiment analysis, machine translation, speech recognition, information retrieval, and
natural language understanding [26].</p>
        <p>The importance of NLP has grown significantly in industrial contexts, especially within safety and
security-critical domains such as automotive, aerospace, and healthcare. In these sectors, vast amounts
of textual data—such as technical documentation, maintenance logs, and safety regulations—must be
processed eficiently and accurately. NLP techniques enable the automation of these processes,
improving both speed and accuracy. For instance, in requirement engineering, NLP is used to extract structured
information from unstructured text, identify key requirements, and even detect inconsistencies or
ambiguities in the text.</p>
        <p>However, despite the advancements in NLP, the field faces significant challenges due to the inherent
complexities of natural language. Language is often ambiguous, context-dependent, and varies greatly
in structure and vocabulary. These characteristics make it dificult for machines to consistently interpret
text in the intended way, particularly in domains where precision and accuracy are critical. For example,
a single requirement written in natural language might be interpreted diferently by diferent readers,
leading to inconsistencies when translating these requirements into formal specifications. Overcoming
these challenges is essential for the efective application of NLP in critical domains, where the stakes
are high and the cost of errors can be severe.</p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. Large Language Models</title>
        <p>Large Language Models [27] represent a major breakthrough in the field of Natural Language Processing,
marking a significant step forward in the ability of machines to understand and generate human-like
text. LLMs, such as OpenAI’s GPT (Generative Pre-trained Transformer) series and Google’s BERT
(Bidirectional Encoder Representations from Transformers), are trained on extensive datasets that
include billions of words from diverse sources such as books, articles, and websites. This vast training
data enables LLMs to learn the statistical properties of language, including grammar, syntax, semantics,
and even some level of contextual understanding.</p>
        <p>One of the key strengths of LLMs lies in their ability to perform a wide range of NLP tasks with
minimal task-specific training, a capability often referred to as “few-shot” or “zero-shot” learning. This
means that LLMs can generalise from a few examples or even tackle tasks they have not been explicitly
trained on. This adaptability makes LLMs highly valuable in various applications, including automated
content generation, dialogue systems, language translation, summarisation, and more.</p>
        <p>In the context of requirement engineering, LLMs ofer a promising solution for the complex task of
translating natural language requirements into formal specifications, such as Property Specification
Patterns. Traditional methods of translation often require deep domain expertise in both the subject
matter and formal languages, making the process time-consuming and prone to errors. LLMs, with their
advanced language understanding capabilities, can assist in this translation by automatically generating
formal specifications from natural language inputs. This not only speeds up the process but also reduces
the likelihood of errors, as LLMs can help ensure that the nuances of the original requirements are
captured accurately in the formal specification.</p>
        <p>The application of LLMs in this domain is particularly valuable in safety and security-critical industries,
where the precision of requirement translation directly impacts the reliability and safety of the final
system. By leveraging LLMs, we can bridge the gap between the informal language used by domain
experts and the formal languages needed for system verification and validation, thereby improving the
overall robustness and safety of industrial systems.</p>
      </sec>
      <sec id="sec-2-3">
        <title>2.3. Property Specification Patterns</title>
        <p>Property Specification Patterns are a powerful formalism used to express system properties in a
structured, standardised, and reusable manner. They are meant to describe the structure of systems’
behaviours and provide expressions of such behaviours in a range of common formalisms. PSPs provide
a high-level, user-friendly language for specifying behavioural properties of systems, such as safety
conditions, liveness, timing constraints, and response requirements. These patterns are designed to be
accessible to engineers and system designers, even those who may not be experts in formal methods or
temporal logic.</p>
        <p>The concept of PSPs was introduced to address the need for a common language that could be used
to specify recurring types of properties across diferent systems. PSPs encapsulate best practices in
formal specification, ofering predefined templates that can be adapted to various contexts. For example,
a safety-critical requirement, such as "The system must never enter an unsafe state," can be expressed
using a standard PSP template, which can then be encoded into a formal language like Linear Temporal
Logic (LTL) [28], Computational Tree Logic (CTL) [29] or Graphical Interval Logic (GIL) [30].</p>
        <p>In safety and security-critical systems, the use of PSPs is particularly important because they help
ensure that requirements are specified in a precise and unambiguous manner, which is crucial for
formal verification and validation. Formal methods, enabled by PSPs, allow for the exhaustive analysis
of system behaviours to verify that they meet all specified requirements. This is particularly critical
in industries such as automotive, aerospace, and medical devices, where even minor errors in system
behaviour can have catastrophic consequences.</p>
        <p>However, translating natural language requirements into PSPs is a complex and challenging task. It
requires not only a deep understanding of the domain-specific requirements but also expertise in formal
languages and formal methods. This dual expertise is often rare, leading to a significant bottleneck in
the requirement specification process.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Abinsula Use Case</title>
      <p>The use case presented in this paper is centred around a real-world application proposed by Abinsula,
a leading Italian company specialising in embedded systems mainly for the Automotive, Medical,
Precise Agriculture and IoT markets. To ensure quality, compliance with the established time limits
and performance reliability, Abinsula formalised its embedded software development procedures. An
important part of these procedures is related to the SW requirements analysis that can be summarised
in the following main steps:</p>
      <sec id="sec-3-1">
        <title>1. Specify the software requirements</title>
        <p>2. Structure software requirements
3. Analyse software requirements against verification criteria
4. Establish bidirectional traceability
5. Ensure consistency between stakeholder requirements and software requirements
Abinsula defined a set of templates to execute these procedures, but none of them is automated.
The work described in this paper sets an important milestone in the path towards the automation of
steps 3 and 5 described in the bullet list above. The specific use case brought by Abinsula involves
the development of a virtual rear-view mirror system, leveraging multiple cooperative cameras and
AI-based technology to enhance vehicle safety and driver awareness. This system captures the external
environment surrounding the vehicle, processing the data in real-time to provide drivers with a
comprehensive view. One of the challenges addressed in this case study are the formal verification of the
system against predefined specifications and ensuring the predictability and reliability of the AI-based
components.</p>
        <p>As in all safety-critical domains, the role of requirements is crucial. This is particularly evident in
this use case, where the development of a virtual rear-view mirror system by Abinsula necessitates
strict adherence to safety standards. Specifically, the ISO 16505:2019 standard, titled "Road Vehicles
— Ergonomic and Performance Aspects of Camera Monitor Systems — Requirements and Test
Procedures" [31], specifies the requirements for camera-monitor systems in road vehicles. The ISO 16505:2019
standard outlines technical guidelines, such as camera placement, resolution, and real-time performance,
to guarantee that the system operates reliably and safely in real-world conditions. This is crucial in the
automotive domain where any failure can result in severe consequences for both human life and the
environment.</p>
        <p>To verify these safety-critical requirements using formal methods, we leveraged PSPs to translate a
set of Abinsula’s requirements from natural language into formal specifications. The set of Abinsula’s
requirements consists of 46 atomic requirements, derived from the ISO 16505:2019 standard and specific
customer needs. These requirements cover various aspects of the system, including safety constraints,
synchronisation, and timing behaviours. The process of formalising these requirements begins with
analysing the natural language descriptions and identifying recurring patterns that reflect common
properties, such as safety, synchronisation, or timing constraints.</p>
        <p>By mapping the linguistic elements of the natural language requirements to the corresponding
patterns in the formal specification language, we developed a catalogue of 40 property specification
patterns tailored to this specific domain. However, while PSPs ofer a robust framework for translating
requirements, the process is not without challenges. To select the appropriate pattern for each
requirement, it is necessary a deep understanding of the system’s domain, of the behaviours being specified,
and of the available patterns. Misidentifying a pattern or failing to capture a specific requirement
can lead to incomplete or incorrect formal specifications. The interpretation and application of these
patterns can also be complex, particularly when handling ambiguous or highly detailed natural language
requirements.</p>
        <p>To illustrate the process of translating natural language requirements into formal specifications
using PSPs, the following table presents a concrete example from the Abinsula use case. Consider the
following requirement from ISO 16505:2019:</p>
        <p>The field of view of the Camera Monitoring System shall cover at least the field of view
required by the national body for conventional mirrors of the same class, both horizontally
and vertically.</p>
        <p>This requirement was partitioned into three atomic requirements expressed in controlled natural
language. Each was analysed using PSP templates to identify its scope and pattern, and then translated
into a formal specification, as detailed in the table below:</p>
        <p>Atomic Requirement</p>
        <p>Scope</p>
        <p>Pattern</p>
        <p>PSP Requirement
IF Class EQUAL 1 AND IF de- Global
fault view THEN vertical vision
distance MUST be EQUAL or
GREATER THAN 60 m behind
driver
IF Class EQUAL 3 AND IF de- Global
fault view THEN vertical vision
distance MUST be EQUAL or
GREATER THAN 20 m behind
driver/passenger
IF Class EQUAL 3 AND IF de- Global
fault view AND vertical
longitudinal median plane EQUAL 20 m
THEN horizontal vision MUST be
EQUAL or GREATER THAN 4 m</p>
        <p>Occurrence - Globally, it is always the case that
Universality if class = 1 and default_view holds,
then vertical_vision_distance &gt;=
60 holds as well.</p>
        <p>Occurrence - Globally, it is always the case that
Universality if class = 3 and default_view holds,
then vertical_vision_distance &gt;=
20 holds as well.</p>
        <p>Occurrence - Globally, it is always the
Universality case that if class = 3 and
default_view and
vertical_longitudinal_median_plane
&gt;= 20 holds, then
horizontal_vision &gt;= 4 holds as well.</p>
        <p>The challenges encountered in this use case, particularly the complexity of translating natural
language requirements into formal specifications, highlight the need for tools like ReqH.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Materials and Methods</title>
      <p>This section outlines the methodology and dataset used in the development and evaluation of ReqH, a
tool designed to facilitate the translation of natural language requirements into Property Specification
Patterns. The following subsections provide a detailed explanation of the methodology employed in
ReqH and describe the dataset utilised in the evaluation process.</p>
      <sec id="sec-4-1">
        <title>4.1. Tool Description</title>
        <p>ReqH is implemented in Python, a language chosen for its versatility and the availability of
robust libraries that facilitate natural language processing and machine learning tasks. The core
functionality of ReqH revolves around its ability to process natural language inputs and generate
corresponding PSPs, a task traditionally requiring both domain expertise and proficiency in formal methods.
The operational framework of ReqH can be broken down into the following key components:
• Preprocessor: The Preprocessor is responsible for preparing the input data. It processes the
natural language requirements contained in a plain text file, ensuring that they are formatted
in a way that is compatible with the subsequent translation steps. This involves standardising
the input format, handling any inconsistencies, and ensuring that the text is clean and ready for
analysis by the LLM.
• Converter: The Converter is the core component of ReqH, where the actual translation of
requirements into PSPs takes place. This component is tightly integrated with the LangChain
library, a powerful tool that provides an interface to various LLMs. LangChain allows users
to select the LLM that best suits their needs, ofering flexibility in terms of model choice and
configuration. During the conversion process, the Converter takes into account both the provided
context (supplied by the user) and configuration parameters, which guide the LLM in generating
the most accurate and relevant PSP translation for each requirement.
• Out Parser: After the requirements have been processed by the Converter, the results are passed
to the Out Parser. The Out Parser is responsible for formatting the translated PSPs according to the
user-defined configuration parameters. This step ensures that the output file, which contains the
PSPs, adheres to any specific formatting requirements or standards that the user may have. The
ifnal output is a plain text file containing the translated PSPs, ready for use in formal verification
and validation processes.</p>
        <sec id="sec-4-1-1">
          <title>The inputs to ReqH include three main components:</title>
          <p>• Req File: A plain text file containing the natural language requirements that need to be translated.
• Context File: A plain text file containing additional context or guidance that the user wishes to
provide to the Converter. This context helps inform the translation process, ensuring that the
LLM has the necessary information to generate accurate PSPs.
• Config Params : A set of configuration parameters that dictate various options for both the
Converter and the Out Parser. These parameters allow users to customise aspects of the translation
process, such as the level of detail in the output or specific formatting preferences.</p>
          <p>The output of ReqH is a plain text file containing the translated requirements in PSP format. This file is
generated after the Out Parser has processed the results from the Converter, ensuring that the PSPs are
correctly formatted and ready for use in formal verification processes.</p>
          <p>The workflow of ReqH proceeds through a straightforward sequence, aimed at ensuring that natural
language requirements are accurately translated into formal specifications. It starts with the user
preparing the necessary inputs, which include the natural language requirements and any relevant
context. These are provided to ReqH in the form of plain text files, along with configuration parameters
that set the specifics for the translation process. Once the inputs are ready, they are processed by the
Preprocessor, which cleans and standardises the data. This step ensures that the requirements are in a
format suitable for translation. Next, the Converter uses the chosen LLM to translate each requirement
into PSPs. The translation process relies on the context and parameters provided, helping to generate
accurate and relevant PSPs. Finally, the translated PSPs go through post-processing by the Out Parser,
which formats them according to the user’s specifications. The end result is a plain text file containing
the PSPs, ready for use in formal verification. This structured methodology makes ReqH a practical
and efective tool for translating natural language requirements into formal specifications, especially in
safety and security-critical areas where precision is crucial.</p>
          <p>A key feature of ReqH is its integration with the LangChain library, which significantly enhances the
tool’s flexibility and adaptability. LangChain provides a seamless interface for building and managing
pipelines that involve various Large Language Models (LLMs), enabling users to select and configure
diferent models according to the specific requirements of their task. This flexibility is crucial in
safety and security-critical domains, where the precision and reliability of requirement translations are
paramount. LangChain ofers extensive control over the parameters of LLMs, such as the temperature
setting. The temperature parameter controls the balance between creativity and coherence in the model’s
output, allowing users to adjust the level of randomness in the generated text. This parameterisation
ensures that ReqH can be finely tuned to produce coherent output corresponding to the PSP syntaxt.
ReqH also leverages Ollama as an execution backend for LLMs to facilitates eficient and scalable model
deployment. Ollama provides a robust infrastructure for running LLMs, making it easier to manage
computational resources and ensuring that the models operate smoothly during the translation process.
For our experimental evaluation, we used the Mistral 7B 1 model, a capable LLM known for handling
complex language tasks with good accuracy and eficiency. Mistral’s design makes it well-suited for
translating detailed requirements in safety-critical domains. While we focused on the Mistral model due
to its efectiveness, ReqH is built to easily accommodate diferent LLMs, allowing it to take advantage
of newer and more advanced models as they become available.</p>
          <p>Finally, it is important to note that the success of ReqH’s translation process is heavily dependent on
both the quality of the selected LLM and the appropriateness of the context provided in the prompt. If
the chosen model or context is not well-suited to the task, the resulting PSP translations may be flawed.
While LLMs like Mistral are highly advanced, they are not infallible, and improper configuration can
lead to suboptimal results. Therefore, careful consideration must be given to the selection of the model
and the crafting of the prompt to ensure accurate and reliable translations.</p>
        </sec>
      </sec>
      <sec id="sec-4-2">
        <title>4.2. Dataset</title>
        <p>In developing a robust dataset for evaluating the ReqH tool, we collaborated closely with domain
experts from Abinsula. We began by working with Abinsula’s experts to create a set of 40 requirements
written in natural language. These requirements were carefully crafted to reflect the typical needs and
constraints encountered in the automotive industry, such as those related to vehicle safety systems,
communication protocols, and other critical functionalities. The selection of these initial requirements
1https://mistral.ai/news/announcing-mistral-7b/
was not arbitrary; it was guided by the intent to cover a wide range of PSPs that are particularly relevant
for the automotive use case under consideration.</p>
        <p>However, while this initial set of 40 requirements provided a solid foundation, we recognised that it
was not suficient for a thorough validation of the proposed methodology. The automotive domain is vast
and complex, and a larger dataset was necessary to adequately assess the efectiveness and reliability of
ReqH. Therefore, we decided to expand our dataset significantly. Using the original 40 requirements as
a base, we employed a semi-automated approach to generate an additional 1000 requirements, along
with their corresponding PSP translations. This expanded dataset was created by varying the original
requirements in ways that would generate new, yet syntactically similar, requirements. These variations
included changes in specific details, such as parameters or conditions, while maintaining the overall
structure and intent of the original requirements. The semi-automated nature of this process allowed
us to eficiently generate a large dataset that still reflected the patterns and complexities typical of
automotive requirements. It is important to note that, while this expanded dataset provides a much
larger sample for evaluation, it may contain requirements with some semantic inconsistencies. These
inconsistencies are a natural consequence of the semi-automated generation process and might include
minor deviations in meaning or context that were not fully aligned with the original intent of the
requirements. However, for the purposes of our current evaluation, these potential semantic issues are
not a primary concern. Our focus in this phase of the research is on assessing the syntactical correctness
of the PSP translations produced by ReqH. By concentrating on syntax, we can objectively measure
how well the tool performs in converting natural language requirements into formal specifications,
without being distracted by the more subjective aspects of semantic accuracy.</p>
        <p>In summary, the final dataset [ 32] used in our evaluation consists of 1000 requirements generated
through a controlled, semi-automated process. This dataset provides a comprehensive basis for testing
the capabilities of ReqH, ensuring that the tool is rigorously evaluated against a wide range of scenarios
that are relevant to the automotive industry and beyond.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Experimental Evaluation</title>
      <p>In this section, we present the experimental evaluation of ReqH, focusing on both the setup and the
results of our experiments. The primary goal of this evaluation is to assess the tool’s efectiveness
in translating natural language requirements into PSP and to verify the syntactical correctness of
these translations. We begin by detailing the experimental setup, outlining the process by which
the requirements were translated and validated. Following this, we present the results, providing
insights into the performance of ReqH and its ability to handle a diverse set of requirements within the
automotive domain.</p>
      <sec id="sec-5-1">
        <title>5.1. Experimental Setup</title>
        <p>You a r e a l a n g u a g e m o d e l s s p e c i a l i z e d f o r t h e c o n v e r s i o n o f
r e q u i r e m e n t s w r i t t e n i n N a t u r a l L a n g u a g e ( NL ) t o P r o p e r t y
S p e c i f i c a t i o n P a t t e r n s ( PSP ) .</p>
        <p>Your o n l y o u t p u t s h o u l d be t h e PSP . Do n o t p r o v i d e any o t h e r o u t p u t
e x c e p t f o r t h e r e q u i r e m e n t i n PSP .</p>
        <p>I n t h e f o l l o w i n g you c a n f i n d some e x a m p l e i n t h e form ’ NL ’ : ’ PSP ’ .
. . .
. . .
. . .</p>
        <p>Now g i v e me t h e PSP c o r r e s p o n d i n g t o t h i s n a t u r a l l a n g u a g e
r e q u i r e m e n t :</p>
        <p>Listing 1: Example of the context file provided to ReqH during our experimental evaluation.</p>
        <p>The requirements from our dataset were sequentially inputted into ReqH. For each requirement, we
employed a consistent context file and set of parameters to guide the translation process. This context
ifle served as the initial part of the prompt provided to the LLM used by ReqH, ensuring that the model
received consistent guidance throughout the evaluation. The format of the context used is detailed in
Listing 1, and it was carefully designed to provide the LLM with the necessary background information
to accurately translate the requirements into PSP format. The requirement examples are not reported
for the sake of clarity: a total of 18 examples were provided in the original context in the format shown.</p>
        <p>For the LLM, we selected the Mistral 7B model, a well-regarded model known for its balance of
performance and eficiency in handling complex language tasks. Given the critical nature of the
requirements in safety and security-focused domains, it was essential to prioritise the coherence and
consistency of the model’s outputs. Therefore, the temperature parameter of the LLM was set to 0. The
temperature setting in LLMs controls the randomness of the model’s responses, with a lower value like
0 reducing variability and encouraging the generation of more predictable, consistent translations. By
setting the temperature to 0, we aimed to maximise the coherence of the translations, ensuring that
each requirement was processed with a high degree of precision.</p>
        <p>After all the requirements were translated using ReqH, the resulting PSPs were subjected to a
syntactical validation process. For this purpose, we used ReqV to systematically evaluate each translated PSP,
identifying any syntactical errors that may have arisen during the translation process. This validation
step was crucial for assessing the reliability of ReqH in producing formally correct specifications that
are suitable for use in verification processes.</p>
        <p>All the code required to replicate our experiment can be found in the ReqH repository 2.</p>
      </sec>
      <sec id="sec-5-2">
        <title>5.2. Experimental Results</title>
        <p>The experimental evaluation of ReqH on our dataset of 1000 requirements yielded a total of 464
successfully translated PSPs. At first glance, this success rate may seem less than ideal, translating less
than half of the provided requirements. However, it is essential to place these results within the broader
context of the task’s complexity.</p>
        <p>Translating natural language requirements into formal specifications is inherently challenging due
to the nuances and ambiguities that often accompany natural language. Natural language is flexible
and expressive, but this flexibility comes at the cost of precision, which is crucial for formal methods.
The automotive domain, with its intricate safety and security requirements, exemplifies the kind of
environment where this challenge is particularly pronounced. Requirements in this field often involve
complex, multi-faceted conditions that can be dificult to capture accurately in formal terms.</p>
        <p>The performance of ReqH, while not perfect, highlights its potential as a valuable tool in the
requirements engineering process, particularly in safety-critical industries like automotive. The tool
successfully handled nearly half of the requirements, demonstrating its capability to assist in the
formalisation of specifications. This is significant, considering that even experienced domain experts
can struggle with translating requirements into precise formal languages.</p>
        <p>Moreover, the results underscore the importance of viewing ReqH as a complementary tool designed
to support domain experts rather than replace them. In contexts where accuracy is paramount — such
as the automotive industry — ReqH can help alleviate the burden of translating requirements, enabling
experts to focus on refining and validating the more complex cases that the tool might not handle
perfectly. By automating the translation of a substantial portion of requirements, ReqH can significantly
reduce the manual efort required in the formalisation process, streamlining workflows and improving
overall eficiency. In this sense, with reference to the SW requirements analysis steps described in
2https://github.com/AIMet-Lab/AIDOaRt-UNISS-ReqH
Section 3, the work presented in this paper allows for the potential automation of step 3 (Analyse
software requirements against verification criteria ) and step 5 (Ensure consistency between stakeholder
requirements and software requirements), therefore counting for the potential automation of 40% of the
steps (2 steps over 5).</p>
        <p>It is also important to note that the success of ReqH in this evaluation is a foundation upon which
future improvements can be built. The results provide valuable insights into the tool’s strengths and
limitations, ofering guidance for further development and fine-tuning. As LLMs continue to advance
and as more domain-specific datasets become available, the performance of tools like ReqH is expected
to improve, making them even more efective in supporting the needs of safety-critical domains.</p>
      </sec>
    </sec>
    <sec id="sec-6">
      <title>6. Conclusions and Future Works</title>
      <p>In this paper, we have introduced ReqH, a tool designed to facilitate the translation of natural language
requirements into PSPs, leveraging the capabilities of LLMs. Our primary focus was on safety and
security-critical domains, particularly within the automotive industry, where the precise formalisation
of requirements is essential for ensuring the integrity and reliability of systems. The experimental
evaluation demonstrated that ReqH was able to successfully translate 464 out of 1000 requirements
into PSPs. While this result indicates that there is room for improvement, it also highlights the inherent
complexity of the task. The process of converting natural language—known for its ambiguity and
variability—into formal specifications is challenging, particularly in domains that demand high levels of
accuracy and precision. Despite these challenges, ReqH has shown promise as a supportive tool for
domain experts. It has been proven to be on the right direction to become useful in the company analysis
of requirements, which is an important part of the company procedures. In particular, the analysis of the
requirements against criteria is time-consuming and error-prone, since it is necessary to check that the
whole set of requirements is atomic, unambiguous, correct, complete, consistent and so on. This could
lead to the overall automation of 40% of procedures related to requirements analysis. By automating the
translation of a significant portion of requirements, ReqH can help reduce the manual efort required in
the formalisation process, allowing experts to focus their attention on more complex cases that require
human judgement and expertise. This approach not only streamlines the workflow but also enhances
the overall eficiency of the requirements engineering process in safety-critical environments.</p>
      <p>Looking forward, there are several avenues for future work to enhance the capabilities and
performance of ReqH. First, improving the accuracy of the translations will be a key focus. This could
involve refining the LLMs used by integrating more advanced models or domain-specific training data.
Additionally, incorporating feedback loops where the output of ReqH is continuously evaluated and
improved based on expert input could help in progressively enhancing the tool’s performance.Finally,
future work could explore the integration of ReqH with other tools in the requirements engineering
process, creating a more comprehensive ecosystem that supports the entire lifecycle of requirement
specification, from natural language capture to formal verification and validation.</p>
      <p>In conclusion, while ReqH is still in its early stages, it ofers a promising approach to addressing the
complex task of translating natural language requirements into formal specifications. With further
development and refinement, ReqH has the potential to become an indispensable tool for ensuring the
accuracy and reliability of systems in safety and security-critical industries.</p>
    </sec>
    <sec id="sec-7">
      <title>Acknowledgments</title>
      <p>This research work has received funding through the AIDOaRt project from the ECSEL Joint Undertaking
(JU) under grant agreement No 101007350. The JU receives support from the European Union’s Horizon
2020 research and innovation programme and Sweden, Austria, Czech Republic, Finland, France, Italy,
and Spain.
[13] D. Guidotti, F. Leofante, L. Pulina, A. Tacchella, Verification and repair of neural networks: A
progress report on convolutional models, in: AI*IA 2019 - Advances in Artificial Intelligence
XVIIIth International Conference of the Italian Association for Artificial Intelligence, Rende, Italy,
November 19-22, 2019, Proceedings, volume 11946 of Lecture Notes in Computer Science, Springer,
2019, pp. 405–417. doi:10.1007/978-3-030-35166-3\_29.
[14] D. Guidotti, F. Leofante, L. Pulina, A. Tacchella, Verification of neural networks: Enhancing
scalability through pruning, in: ECAI 2020 - 24th European Conference on Artificial Intelligence,
29 August-8 September 2020, Santiago de Compostela, Spain, August 29 - September 8, 2020
- Including 10th Conference on Prestigious Applications of Artificial Intelligence (PAIS 2020),
volume 325 of Frontiers in Artificial Intelligence and Applications , IOS Press, 2020, pp. 2505–2512.
doi:10.3233/FAIA200384.
[15] D. Guidotti, L. Pulina, A. Tacchella, pynever: A framework for learning and verification of neural
networks, in: Automated Technology for Verification and Analysis - 19th International Symposium,
ATVA 2021, Gold Coast, QLD, Australia, October 18-22, 2021, Proceedings, volume 12971 of Lecture
Notes in Computer Science, Springer, 2021, pp. 357–363. doi:10.1007/978-3-030-88885-5\_23.
[16] S. Demarchi, D. Guidotti, Counter-example guided abstract refinement for verification of neural
networks, in: Proceedings of the CPS Summer School PhD Workshop 2022 co-located with 4th
Edition of the CPS Summer School (CPS 2022), Pula, Sardinia (Italy), September 19-23, 2022, volume
3252 of CEUR Workshop Proceedings, CEUR-WS.org, 2022.
[17] D. Guidotti, Verification of neural networks for safety and security-critical domains, in: Proceedings
of the 10th Italian workshop on Planning and Scheduling (IPS 2022), RCRA Incontri E Confronti
(RiCeRcA 2022), and the workshop on Strategies, Prediction, Interaction, and Reasoning in Italy
(SPIRIT 2022) co-located with 21st International Conference of the Italian Association for Artificial
Intelligence (AIxIA 2022), November 28 - December 2, 2022, University of Udine, Udine, Italy,
volume 3345 of CEUR Workshop Proceedings, CEUR-WS.org, 2022.
[18] D. Guidotti, L. Pandolfo, L. Pulina, Verifying neural networks with non-linear SMT solvers: a short
status report, in: 35th IEEE International Conference on Tools with Artificial Intelligence, ICTAI
2023, Atlanta, GA, USA, November 6-8, 2023, IEEE, 2023, pp. 423–428. doi:10.1109/ICTAI59109.
2023.00068.
[19] D. Guidotti, L. Pandolfo, L. Pulina, Verification of nns in the IMOCO4.E project: Preliminary results,
in: 28th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA
2023, Sinaia, Romania, September 12-15, 2023, IEEE, 2023, pp. 1–4. doi:10.1109/ETFA54631.
2023.10275345.
[20] D. Guidotti, L. Pandolfo, L. Pulina, Verifying neural networks with SMT: an experimental evaluation,
in: 19th IEEE International Conference on e-Science, e-Science 2023, Limassol, Cyprus, October
9-13, 2023, IEEE, 2023, pp. 1–2. doi:10.1109/E-SCIENCE58273.2023.10254877.
[21] S. Demarchi, D. Guidotti, L. Pulina, A. Tacchella, Supporting standardization of neural networks
verification with VNNLIB and coconet, in: Proceedings of the 6th Workshop on Formal Methods for
ML-Enabled Autonomous Systems, FoMLAS@CAV 2023, Paris, France, July 17-18, 2023, volume 16
of Kalpa Publications in Computing, EasyChair, 2023, pp. 47–58. doi:10.29007/5PDH.
[22] D. Guidotti, L. Pandolfo, L. Pulina, Formal verification of neural networks: A "step zero" approach
for vehicle detection, in: Advances and Trends in Artificial Intelligence. Theory and Applications
- 37th International Conference on Industrial, Engineering and Other Applications of Applied
Intelligent Systems, IEA/AIE 2024, Hradec Kralove, Czech Republic, July 10-12, 2024, Proceedings,
volume 14748 of Lecture Notes in Computer Science, Springer, 2024, pp. 297–309. doi:10.1007/
978-981-97-4677-4\_25.
[23] D. Guidotti, L. Pandolfo, L. Pulina, Verifying autoencoders for anomaly detection in predictive
maintenance, in: Advances and Trends in Artificial Intelligence. Theory and Applications
37th International Conference on Industrial, Engineering and Other Applications of Applied
Intelligent Systems, IEA/AIE 2024, Hradec Kralove, Czech Republic, July 10-12, 2024, Proceedings,
volume 14748 of Lecture Notes in Computer Science, Springer, 2024, pp. 188–199. doi:10.1007/
978-981-97-4677-4\_16.
[24] D. Guidotti, F. Leofante, A. Tacchella, C. Castellini, Improving reliability of myocontrol using
formal verification, IEEE Transactions on Neural Systems and Rehabilitation Engineering 27 (2019)
564–571. doi:10.1109/TNSRE.2019.2893152.
[25] M. B. Dwyer, G. S. Avrunin, J. C. Corbett, Patterns in property specifications for finite-state
verification, in: Proceedings of the 1999 International Conference on Software Engineering, ICSE’
99, Los Angeles, CA, USA, May 16-22, 1999, ACM, 1999, pp. 411–420. doi:10.1145/302405.
302672.
[26] N. Patwardhan, S. Marrone, C. Sansone, Transformers in the real world: A survey on NLP
applications, Inf. 14 (2023) 242. doi:10.3390/INFO14040242.
[27] P. Kumar, Large language models (llms): survey, technical frameworks, and future challenges,</p>
      <p>Artif. Intell. Rev. 57 (2024) 260. doi:10.1007/S10462-024-10888-Y.
[28] A. Pnueli, Z. Manna, The temporal logic of reactive and concurrent systems, Springer 16 (1992) 12.
[29] E. M. Clarke, E. A. Emerson, A. P. Sistla, Automatic verification of finite-state concurrent systems
using temporal logic specifications, ACM Transactions on Programming Languages and Systems
(TOPLAS) 8 (1986) 244–263.
[30] L. K. Dillon, G. Kutty, L. E. Moser, P. M. Melliar-Smith, Y. S. Ramakrishna, A graphical interval logic
for specifying concurrent systems, ACM Transactions on Software Engineering and Methodology
(TOSEM) 3 (1994) 131–165.
[31] I. O. for Standardization, Road vehicles — Ergonomic and performance aspects of Camera Monitor
Systems — Requirements and test procedures, ISO 16505:2019 ed., International Organization for
Standardization, Vernier, Geneva, Switzerland, 2019. URL: https://www.iso.org/standard/72000.
html.
[32] D. Guidotti, L. Pandolfo, L. Pulina, S. Azzena, Automotive Domain Property Specification Pattern
Dataset, 2024. doi:10.5281/zenodo.13373276.</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          [1]
          <string-name>
            <given-names>D.</given-names>
            <surname>Aineto</surname>
          </string-name>
          , R. De Benedictis,
          <string-name>
            <given-names>M.</given-names>
            <surname>Maratea</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Mittelmann</surname>
          </string-name>
          ,
          <string-name>
            <given-names>G.</given-names>
            <surname>Monaco</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Scala</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Serafini</surname>
          </string-name>
          ,
          <string-name>
            <given-names>I.</given-names>
            <surname>Serina</surname>
          </string-name>
          ,
          <string-name>
            <given-names>F.</given-names>
            <surname>Spegni</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Tosello</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Umbrico</surname>
          </string-name>
          , M. Vallati (Eds.),
          <source>Proceedings of the International Workshop on Artificial Intelligence for Climate Change, the Italian workshop on Planning and Scheduling</source>
          , the RCRA Workshop on
          <article-title>Experimental evaluation of algorithms for solving problems with combinatorial explosion, and</article-title>
          the Workshop on Strategies, Prediction, Interaction, and
          <article-title>Reasoning in Italy (AI4CC-IPS-RCRA-SPIRIT 2024), co-located with 23rd International Conference of the Italian Association for Artificial Intelligence</article-title>
          (AIxIA
          <year>2024</year>
          ), CEUR Workshop Proceedings, CEUR-WS.org,
          <year>2024</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          [2]
          <string-name>
            <given-names>J.</given-names>
            <surname>Heckmann</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Shirlaw</surname>
          </string-name>
          ,
          <article-title>An industrial view of requirements engineering and safety</article-title>
          , in: G. Rabe (Ed.), 14th International Conference on Computer Safety, Reliability and Security,
          <source>Safecomp</source>
          <year>1995</year>
          , Belgirate, Italy,
          <source>October 11-13</source>
          ,
          <year>1995</year>
          , Springer,
          <year>1995</year>
          , pp.
          <fpage>411</fpage>
          -
          <lpage>416</lpage>
          . doi:
          <volume>10</volume>
          .1007/ 978-1-
          <fpage>4471</fpage>
          -3054-3\_
          <fpage>28</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          [3]
          <string-name>
            <given-names>S.</given-names>
            <surname>Jones</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Till</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A. M.</given-names>
            <surname>Wrightson</surname>
          </string-name>
          ,
          <article-title>Formal methods and requirements engineering: Challenges and synergies</article-title>
          ,
          <source>J. Syst. Softw</source>
          .
          <volume>40</volume>
          (
          <year>1998</year>
          )
          <fpage>263</fpage>
          -
          <lpage>273</lpage>
          . doi:
          <volume>10</volume>
          .1016/S0164-
          <volume>1212</volume>
          (
          <issue>97</issue>
          )
          <fpage>00171</fpage>
          -
          <lpage>4</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          [4]
          <string-name>
            <given-names>A.</given-names>
            <surname>Yasin</surname>
          </string-name>
          ,
          <string-name>
            <given-names>T.</given-names>
            <surname>Su</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Pillement</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M. J.</given-names>
            <surname>Ciesielski</surname>
          </string-name>
          ,
          <article-title>Formal verification of divider circuits by hardware reduction</article-title>
          ,
          <source>in: 19th International Conference on Synthesis, Modeling, Analysis and Simulation Methods</source>
          and Applications to Circuit Design,
          <string-name>
            <surname>SMACD</surname>
          </string-name>
          <year>2023</year>
          , Funchal,
          <source>Portugal, July 3-5</source>
          ,
          <year>2023</year>
          , IEEE,
          <year>2023</year>
          , pp.
          <fpage>1</fpage>
          -
          <lpage>4</lpage>
          . doi:
          <volume>10</volume>
          .1109/SMACD58065.
          <year>2023</year>
          .
          <volume>10192137</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          [5]
          <string-name>
            <given-names>L.</given-names>
            <surname>Pandolfo</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Pulina</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Vuotto</surname>
          </string-name>
          ,
          <article-title>Smt-based consistency checking of configuration-based components specifications</article-title>
          ,
          <source>IEEE Access 9</source>
          (
          <year>2021</year>
          )
          <fpage>83718</fpage>
          -
          <lpage>83726</lpage>
          . doi:
          <volume>10</volume>
          .1109/ACCESS.
          <year>2021</year>
          .
          <volume>3085911</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          [6]
          <string-name>
            <given-names>G.</given-names>
            <surname>Katz</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C. W.</given-names>
            <surname>Barrett</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D. L.</given-names>
            <surname>Dill</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K.</given-names>
            <surname>Julian</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M. J.</given-names>
            <surname>Kochenderfer</surname>
          </string-name>
          ,
          <string-name>
            <surname>Reluplex:</surname>
          </string-name>
          <article-title>An eficient SMT solver for verifying deep neural networks</article-title>
          , in: Computer Aided Verification - 29th
          <source>International Conference, CAV 2017</source>
          , Heidelberg, Germany,
          <source>July 24-28</source>
          ,
          <year>2017</year>
          , Proceedings,
          <string-name>
            <surname>Part</surname>
            <given-names>I</given-names>
          </string-name>
          , volume
          <volume>10426</volume>
          of Lecture Notes in Computer Science, Springer,
          <year>2017</year>
          , pp.
          <fpage>97</fpage>
          -
          <lpage>117</lpage>
          . doi:
          <volume>10</volume>
          .1007/978-3-
          <fpage>319</fpage>
          -63387-9\_5.
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          [7]
          <string-name>
            <given-names>D.</given-names>
            <surname>Guidotti</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Pandolfo</surname>
          </string-name>
          , L. Pulina,
          <article-title>Leveraging satisfiability modulo theory solvers for verification of neural networks in predictive maintenance applications</article-title>
          ,
          <source>Inf</source>
          .
          <volume>14</volume>
          (
          <year>2023</year>
          )
          <article-title>397</article-title>
          . doi:
          <volume>10</volume>
          .3390/ INFO14070397.
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          [8]
          <string-name>
            <given-names>S.</given-names>
            <surname>Demarchi</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Guidotti</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Pitto</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Tacchella</surname>
          </string-name>
          ,
          <article-title>Formal verification of neural networks: A case study about adaptive cruise control</article-title>
          ,
          <source>in: Proceedings of the 36th ECMS International Conference on Modelling and Simulation, ECMS</source>
          <year>2022</year>
          , Ålesund, Norway, May 30 - June 3,
          <year>2022</year>
          ,
          <source>European Council for Modeling and Simulation</source>
          ,
          <year>2022</year>
          , pp.
          <fpage>310</fpage>
          -
          <lpage>316</lpage>
          . doi:
          <volume>10</volume>
          .7148/2022-0310.
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          [9]
          <string-name>
            <given-names>D.</given-names>
            <surname>Guidotti</surname>
          </string-name>
          ,
          <article-title>Enhancing neural networks through formal verification</article-title>
          ,
          <source>in: Discussion and Doctoral Consortium papers of AI*IA 2019 - 18th International Conference of the Italian Association for Artificial Intelligence</source>
          , Rende, Italy,
          <source>November 19-22</source>
          ,
          <year>2019</year>
          , volume
          <volume>2495</volume>
          <source>of CEUR Workshop Proceedings, CEUR-WS.org</source>
          ,
          <year>2019</year>
          , pp.
          <fpage>107</fpage>
          -
          <lpage>112</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          [10]
          <string-name>
            <given-names>R.</given-names>
            <surname>Eramo</surname>
          </string-name>
          ,
          <string-name>
            <given-names>T.</given-names>
            <surname>Fanni</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Guidotti</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Pandolfo</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Pulina</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K.</given-names>
            <surname>Zedda</surname>
          </string-name>
          ,
          <article-title>Verification of neural networks: Challenges and perspectives in the aidoart project (short paper)</article-title>
          ,
          <source>in: Proceedings of the 10th Italian workshop on Planning and Scheduling (IPS</source>
          <year>2022</year>
          ), RCRA Incontri E Confronti (RiCeRcA
          <year>2022</year>
          ), and the workshop on Strategies, Prediction, Interaction, and
          <article-title>Reasoning in Italy (SPIRIT 2022) co-located with 21st International Conference of the Italian Association for Artificial Intelligence</article-title>
          (AIxIA
          <year>2022</year>
          ),
          <source>November 28 - December 2</source>
          ,
          <year>2022</year>
          , University of Udine, Udine, Italy, volume
          <volume>3345</volume>
          <source>of CEUR Workshop Proceedings, CEUR-WS.org</source>
          ,
          <year>2022</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          [11]
          <string-name>
            <given-names>D.</given-names>
            <surname>Guidotti</surname>
          </string-name>
          ,
          <article-title>Safety analysis of deep neural networks</article-title>
          ,
          <source>in: Proceedings of the Thirtieth International Joint Conference on Artificial Intelligence, IJCAI</source>
          <year>2021</year>
          , Virtual Event / Montreal, Canada,
          <fpage>19</fpage>
          -27
          <source>August</source>
          <year>2021</year>
          ,
          <article-title>ijcai</article-title>
          .org,
          <year>2021</year>
          , pp.
          <fpage>4887</fpage>
          -
          <lpage>4888</lpage>
          . doi:
          <volume>10</volume>
          .24963/IJCAI.
          <year>2021</year>
          /675.
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          [12]
          <string-name>
            <given-names>D.</given-names>
            <surname>Guidotti</surname>
          </string-name>
          ,
          <article-title>Verification and repair of neural networks</article-title>
          ,
          <source>in: Thirty-Fifth AAAI Conference on Artificial Intelligence</source>
          ,
          <source>AAAI 2021, Thirty-Third Conference on Innovative Applications of Artificial Intelligence, IAAI</source>
          <year>2021</year>
          ,
          <source>The Eleventh Symposium on Educational Advances in Artificial Intelligence, EAAI</source>
          <year>2021</year>
          ,
          <string-name>
            <given-names>Virtual</given-names>
            <surname>Event</surname>
          </string-name>
          ,
          <source>February 2-9</source>
          ,
          <year>2021</year>
          , AAAI Press,
          <year>2021</year>
          , pp.
          <fpage>15714</fpage>
          -
          <lpage>15715</lpage>
          . doi:
          <volume>10</volume>
          .1609/AAAI.V35I18.17854.
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>