=Paper= {{Paper |id=Vol-3777/paper24 |storemode=property |title=Trustworthy AI Systems from Untrustworthy Components: Development von Neumann’s Paradigm using Principle of Diversity |pdfUrl=https://ceur-ws.org/Vol-3777/paper24.pdf |volume=Vol-3777 |authors=Vyacheslav Kharchenko,Oleg Odarushchenko |dblpUrl=https://dblp.org/rec/conf/profitai/KharchenkoO24 }} ==Trustworthy AI Systems from Untrustworthy Components: Development von Neumann’s Paradigm using Principle of Diversity== https://ceur-ws.org/Vol-3777/paper24.pdf
                                Trustworthy AI Systems from Untrustworthy
                                Components: Development von Neumann’s Paradigm
                                using Principle of Diversity
                                Vyacheslav Kharchenko1 and Oleg Odarushchenko2
                                1
                                    National Aerospace University KhAI, Vadym Manko str., 17, Kharkiv, 61070, Ukraine
                                2
                                    Poltava State Agrarian University, Skovorody str., 1/3, Poltava, 36003, Ukraine

                                                                    Abstract
                                                                    The article discusses possibilities of creating trustworthy and explainable artificial intelligence (AI) and AI-
                                                                    based systems (AIS) using well-known von Neumann’s paradigm (VNP). The models of AI and AIS quality
                                                                    are analyzed focusing on the most challengeable attributes related to trustworthiness of AI, safety and
                                                                    security of AISs. Framework of analysis, VPN formulations, methods of implementation, and stages of
                                                                    evolution VNP (in context of dependable and resilient systems and infrastructures) including stage of
                                                                    creating AISs and particularities of implementing the paradigm for various AI quality attributes are
                                                                    described. An approach and mathematical models describing application of diversity principles to built
                                                                    trustworthy AIS out of not enough trustworthy AI components (channels) are developed and investigated.
                                                                    A problem of AIS “immortality”, the research results and future steps are discussed.

                                                                    Keywords
                                                                    Artificial intelligence, trustworthiness, safety, two-version AI system, common cause failure 1


                                1. Introduction
                                           1.1. Motivation

                                The development and implementation of methods, tools and technologies of artificial intelligence
                                (AI) take place in three main directions. The first direction concerns the improvement of various
                                services to improve the quality of life, the performance of functions that provide greater comfort and
                                convenience in everyday life, business and finance [1, 2]. The second direction is related to the use
                                of AI for developing algorithms and control tools for industry, transport, power stations and grids,
                                etc. [3, 4, 5, 6].
                                    The third direction can be formulated as the one related to the reliability and security problems
                                of artificial intelligence and by analogy with the well-known term safeware proposed by N. Levenson
                                [7], it can be defined as AI safeware (AISaW) or AI secureware (AISeW). It is clear that this direction
                                is related to the first two, since reliability and safety issues are very important there.
                                    There are many cases when the unpredictable and erroneous behavior of AI means led to
                                catastrophic consequences for services and systems of the first and second mentioned directions [8,
                                9]. Their analysis, as well as the forecast of an increase in AI vulnerabilities and threats of cyber
                                attacks, as well as specific failures of intelligent systems, led to the reaction of well-known specialists
                                with a call to slow down and even stop the development and distribution of AI products, the use of
                                service ChatGPT, etc. [10, 11].
                                    Therefore, it is urgent to find solutions that would harmonize the first two directions with the
                                third one and ensure the predicted, reliable and safe functioning of AI systems. Such solutions can
                                be based on the use of various types of testing AI behavior, application of redundancy, means of
                                tolerance and protection from the consequences of anomalous behavior caused by hidden


                                ProfIT AI 2024: 4th International Workshop of IT-professionals on Artificial Intelligence (ProfIT AI 2024), September 25–27,
                                2024, Cambridge, MA, USA
                                   v.kharchenko@csn.khai.edu (V. Kharchenko); odarushchenko@gmail.com (O. Odarushchenko)
                                        0000-0001-5352-077X (V. Kharchenko); 0000-0003-3933-9637 (O. Odarushchenko)
                                                               © 2024 Copyright for this paper by its authors.
                                                               Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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vulnerabilities and faults, non-compliance with requirements, as well as failures of software and
hardware platforms of intelligent systems.

    1.2. State of the art

    In the context of safety and security, artificial intelligence is considered from three positions [12]:
AI as a safety/security object (AI as an asset that must be protected, AIaSO); AI as a means of ensuring
safety/security or the so-called AI powered protection (AI as an asset for protection, AIaSP); AI as a
means of breaching safety/security or so-called AI powered attacks (AI as an asset for an attack,
AIaSA). The same division is possible from the point of view of any other characteristics X (AIaXO,
AIaXP, AIaXA) such as reliability, dependability, resilience, trustworthiness and others. According
to [13], eighth main scenarios can be considered depending on cases Yes/No on three options, for
example, for security and AI.
    This research focuses on the first issue when it is necessary to ensure the reliability, safety, and
specific characteristics of AI and AI systems using different kinds of redundancy. There are many
publications related to direction AIaXO and dedicated to various aspects of assessment, development
and implementation of methods and means for providing required characteristics X of intelligent
systems [14, 15, 16]. However, we attended for further investigation based on classical work of John
von Neumann "Probabilistic Logics and the Synthesis of Reliable Organisms from Unreliable
Components" proposed in 1952 [17].
    Concept of “wide” dependability as a federative attribute joining reliability, maintainability,
availability, safety, integrity [18] became a logical development of the paradigm “building reliable
computer systems with unreliable components” [19]. It is important to note that von Neumann had
in mind the use of the principles of high availability and redundancy, primarily for hardware (HW)
that was the main reason of computer system failures. In the process of development of computer
technology and information systems, the share of HW failures gradually decreased compared to
failures caused by software (SW) design faults [20].
    This led to the development of the VNP by other researchers, in particular authors of [21] and
[22] suggested methodology of N-version programming and the concept of building dependable
systems from undependable components correspondingly. The next stage of development is the
formulation of the dependability concept for a specific class of systems such as the concept of
creating dependable service-oriented systems from not enough dependable web-components with
uncertain characteristics [22]. The methodology of building safe systems and infrastructures from
insufficiently safe systems is considered in [23]. The development of the VNP was extended to cloud
IT-infrastructure and I&C systems with multipurpose maintenance [24, 25].
    As a preliminary conclusion, it should be noted that, on the one hand, the specific features of AI
models and tools are not taken into account in a certain way within the framework of the
development of VNP principles; on the other hand, a large number of publications regarding the
provision of AI trustworthiness, explainability, ethics, etc., almost do not take into account systemic
problems of dependability, safety, etc.

    1.3. Objectives and structure

   The aim of the research is to analyze possibilities of application von Neumann’s paradigm (VNP)
and VNP-based solutions to improve trustworthiness and other characteristics of AI systems. The
objectives are the following:
   •    to discuss AI quality models [24], their characteristics and sub-characteristics to determine
   which of them and how can be improved by use of VNP-based approach;
   •    to analyze stages of VNP evolution to justify possible options for implementation of the
   paradigm for providing trustworthiness and other AI characteristics;
    •    to develop and investigate models of trustworthy and safe AI systems which are based on
    application of diversity principle or version redundancy (VR) on creating redundant channels and
    implement VNP using such approach.
    The structure of the paper is as follows: Section 2 analyzes models of AI and AI systems quality
focusing on the most challengeable attributes related to trustworthiness of AI, safety and security of
AI systems; Section 3 discussed structure and stages of development VNP (in context of dependable
and resilient systems and infrastructures) including stage of creating AI systems and particularities
of implementing the paradigm for various AI quality attributes; Section 4 presents approach, solution
and mathematical models describing application of diversity principles to built trustworthy AI
system out of not enough trustworthy AI components (channels); Section 5 discuss the results of
investigations and concerns a problem of AI and AI systems immortality; the final Section 6
summarizes and describes future research directions.

2. Model of AI systems quality: trustworthiness
In order to answer the question of how VNP can be developed and used to improve the specific
dependability related characteristics of intelligent systems, it is necessary to determine the features
of the AI characteristics. For this, it is suggested to use the quality model suggested in [26]. The
model of AI systems quality consists of two parts or sub-models. First one is the actual artificial
intelligence quality model; the second part is the quality model of the software-hardware platform
that implements the functional algorithms of artificial intelligence in accordance with the
requirements. Table 1 describes a simplified, so-called [26] basic AI quality model, which generally
has a three-level structure and includes 32 characteristics. The basic version provides a two-level
model, with five characteristics of the first level and 16 sub-characteristics that form the second level
and are detailed characteristics of AI.
Table 1
Model of AI quality simplifying according to [26]
  Charac-          Definition                                               Sub-characteristics
  teristics
  Ethics,      The ability of AI to meet current standards of          Fairness, FRN;                    H
  ETH          morality on the results of functioning                   Graspability, GRS;
                                                                               Human agency, HMA;
                                                                               Redress, RDR
  Lawful-      Ability of AI to comply with laws and regulations       No                                R
  ness, LFL
  Explai-      The ability of AI to be understood and predictable      Completeness, CMT;                H
  nability,    in terms of purpose and behavior                           Comprehensibility, MH;
  EXP                                                                           Interpretability, INP;
                                                                                Interactivity, INR;
                                                                                Transparency, TRP;
                                                                                Verifiability, VFB
  Respon-      Ability of AI to function considering the expectations No                                 H
  sibility,     of the client (user) in accordance with ethical norms,
  RSP          legal regulations, as well as to inform him in case of
               possible violation
  Trustwor-    Ability of AI, characterized by the degree of             Accuracy, ACR;                  H
  thiness,     confidence of the stakeholders, developers,              Diversity, DVS;
  TST          auditors, etc.) that the AI meets and performs its      Resilience, RSL;
               functions in a predictable manner                          Robustness, RBS;
                                                                                 Safety, SFT;
                                                                                 Security, SCR
   The table defines the characteristics of ethics (ETH), lawfulness (LFL), explainability (EXP),
responsibility (RSP), trustworthiness (TST), as well as a list of relevant sub-characteristics and their
codification in alphabet order.
   The definition of characteristics and sub-characteristics was performed on the basis of the
analysis of a large number of articles and regulatory documents in accordance with the methodology
described in [26]. This technique was based on semantic analysis, selection, and harmonization of
definitions. It should be noted that in two years many new normative documents of various levels
regarding the characteristics of AI [27]. However, in our opinion, this does not fundamentally affect
the conclusions of this study.
   The second part of the quality model of AI systems, namely their platforms, consists of two
subsets: a subset more traditional characteristics, namely [26]: auditability (ADT), availability (AVL),
controllability (CNT), effectiveness (EFS), reliability (RLB), maintainability (MNT), sustainability
(SST), usability (USB); a subset of sub-characteristics (so-called group, AIG) crossing with AI
trustworthiness sub-characteristics such as accuracy (ACR), diversity (DVS), resiliency (RSL),
robustness (RBS), safety (SFT), security (SCR), and sub-characteristics verifiability (VFB) of
explainability.
   The main differences between the AI quality model and the SW quality models: presence of
specific characteristics, namely ethics, legality, etc.; definition as the main characteristics of
trustworthiness, explainability and responsibility; subordination of such important, primary
characteristics of traditional (critical) systems as safety, security, resilience and others to the key
characteristic of AI trustworthiness; filling explainability with a set of known (VFB) and relatively
new sub-characteristics such as comprehensibility, interpretability and others.

3. Evolution of Von Neumann’ paradigm: a stage of developing
   trustworthy and explainable AI systems
The development and enhancing of intelligent systems contributes to the further advancement and
expansion of the VNP. Initially, the development of VNP for AI systems can take place in an
understandable way, when such systems are considered as software and hardware implementation
of certain functions and the key is the question of their reliable (dependable) functioning.
    Then VNP can be formulated as "a reliable AI system with insufficiently reliable (AI or any other)
components" in the simplest option or detail this formulation in view of the evolution of computer
systems as such.
    This approach is quite acceptable if we are talking about the software and hardware platform of
the AI system, which is distinguished in the quality model of AI systems, the main component of
which is the AI itself (the corresponding models and algorithms). However, if the specific
attributes/characteristics of the qualities of AI itself, such as trustworthiness, explainability, ethics
and so on, are taken into account, the paradigm should be formulated and developed more carefully.
    This is due to the fact that, according to own ideology, AI can have so-called natural properties
in some characteristics. In particular, it is about natural resilience, robustness, etc. [28].
    Therefore, the formulation of VNP for AI systems should be based on the most important and
quite specific AI characteristics, first of all, trustworthiness integrating several essential sub-
characteristics, such as diversity, resilience, etc. Other specific AI characteristics (explainability,
ethics, lawfulness) are interesting to analyze from the point of view of the possibility of applying and
implementing VNP for their improvement.

    3.1. VNP evolution analysis

   Figure 1 provides describing the stages and entity of paradigm evolution in two-coordinate space
“stages (systems/components/component properties) – system properties (reliability, availability,
safety, dependability,…)” which is added by methods of VPN implementation.
Figure 1: Diagram of VNP evolution including stage of AI systems development

    The objects of analysis are evolutionary stages, systems, components, and their properties, which
are the material embodiment of the respective stage. Elements of evolution-based methodology for
analyzing transformation of VNP were suggested and investigated in work [29] describing evolution
stages without AI systems. A formula of VNP can be presented by the following tuple:
                           VNP = < {Proc}, {CharS}, {Syst}, From, {CharC}, {Comp}>,                     (1)
    where {Proc} – a set of processes (synthesis, development, creation,…); {CharS} – a set of
characteristics of system (reliable, dependable, safe, secure, resilient, trustworthy,…); {Syst} – a set of
systems (device, system, infrastructure,… that are synthesized, developed, created,…); From – a
preposition connecting system Syst and its components Comp (Syst X from Comp Y); {CharC} – a
set of characteristics of component that part of system Syst (usually they are antipodes of CharS:
unreliable or not enough reliable, unsafe, undependable, unresilient, untrustworthy); {Comp} – a set
of components (relay, integral circuit/chip, hardware, software, system,… used to built system Syst.
    It is clear that a part of elements-tuples of the SVNP will be empty. Figure 1 describes a fragment
of VNP evolution during seven stages (1950-2020 years), every of which is presented by one of the
formulations (3) beginning from initial simplest expression “Synthesis of reliable devices form
unreliable (not enough reliable) relays” (1950 years, applied method – structure static redundancy)
and formulation of 2010th years “Development (deployment) of dependable IT-infrastructures from
undependable systems (services with uncertain and varying characteristics)”. As for AI systems
(seventh stage, 2020 years), several VNP formulations are also possible depending on which
characteristics or sub-characteristics are considered. The most general is “Development of
trustworthy (and/or explainable) AI systems from untrustworthy (unexplainable) AI components”.
    3.2. VNP for AI systems: options

   Table 2 describes possibilities of VNP implementation for AI systems taking into account various
characteristics and sub-characteristics.

Table 2
Analysis of methods for VNP implementation for AI characteristics
  AI cha-   AI sub-   VNP       Methods applied for           Notes
  rac-      charac-   appli-    VNP implementation
  teri-     teris-    cation
  stics     tics      (Y/N)
   TST       In ge-             Methods applied for        Compatability of these methods and means
            neral     Yes       sub-characteristics        should be taken into account
            DVS       Yes       Version redundancy         Problem is developing and choosing versions
                                                           with maximal diversity metrics
            RSL       Yes       Proactivity,    version    The same. Besides, problems is in
                                and structural re-         development and implementation of means
                                dundancy, dynamical        providing    proactivity and  dynamical
                                reconfiguration            reconfiguration
            RBS       Yes       Version redundancy         Problem is developing and choosing versions
                                                           with maximal diversity in point of view input
                                                           data
            SFT       Yes       Version and struc-tural    Main criteria of implemented methods and
                                redundancy                 means is minimizing risks of CCF
            SCR       Yes/      VR for integrity and       Use of VR must be defined considering impact
                      No        accessibility              on the different security attributes
            ACR       Yes       Version, time, struc-      Main criteria is decreasing total errors
                                tural redundancy
  EXP       In ge-    No        -                          Redundancy      can     increase     level     of
            neral                                          unexplainability
  RSP       In ge-    Yes       Version,      structural   RSP is dependent on credibility,
            neral               redundancy, dynami-        explainability, etc. It should be taken into
                                cal reconfiguration        account on choice of the methods
  ETH       In ge-    No        -                          VR can be applied if the versions will provi-
            neral                                          de different reactions on situations with
                                                           ethically unacceptable alternatives
  LFL       In ge-    No        -                          VR can be applied if the versions will provide
            neral                                          different reactions on so called situations
                                                           with unacceptable alternatives in point of
                                                           view lawfulness


   VNP can be developed and applied to technologies in which AI-based solutions directly and
effectively embedded. This applies, in particular, to IoT/IoE technologies. Known branches of these
technologies are integrated with AI, namely the so-called Internet of Artificial Intelligence Things
(IoAIT), Internet of Artificial Intelligence (IoAI), Artificial Intelligence of Things (AIoT) and so on.
   AIoT is defined as the combination of Artificial intelligence technologies with the IoT
infrastructure to achieve more efficient IoT operations, improve human-machine interactions and
enhance data management and analytics.
   Hence, VNP that was formulated for IoT system as Dependable Internet of Undependable (not
enough Dependable) Things, DIoUDT, and implemented by application of redundant nodes and
communications, can be reformulated as a Trustworthy Artificial Intelligence from Untrustworthy
(not enough Trustworthy) Things, TAIoUTT. More problematic is developing such systems
considering characteristics of explainability and ethics.

4. Application of diversity for creating trustworthy AI systems out of
   untrustworthy AI components
    4.1. Principle of diversity for developing trustworthy and safe AI systems

In the early stages of development, VNP was based exclusively on the use of structural redundancy.
Later, when the productivity of eleсtronic components and computers increased, and, as a result,
some reserves of time appeared, the redundancy based on the use of such reserves added the
structural redundancy. Therefore, the temporal redundancy strengthened the structural one and
improved the dynamics of the development of some branches of the VNP.
    However, the next idea, the idea of N-version programming became truly revolutionary for VNP
[21]. Later, it developed into the principles of multi-version design and multi-version systems [22,
25]. Version redundancy together with structural and temporal redundancy formed a specific
redundancy base for VNP and fault- and intrusion tolerant systems of a very wide class.
    The application of structural and temporal redundancy cannot protect the AI system, as well as
digital systems in general, from failures caused by design faults, programming errors, giving rise to
so-called common cause failures (CCF), since they are replicated on backup channels and repeated
with additional phases of calculations.
    Version redundancy, which equates to the principle of diversity, when the same task is
implemented using different programming languages and teams of programmers, developers,
verifiers, different environments and development tools, different software and hardware platforms,
different life cycle models etc., significantly reduces the ССF risks [30].
    The implementation of the principle of diversity for intelligent systems in terms of actual AI
models and algorithms has its essential specificity. The task of classifying and researching types of
diversity for AI is an independent task.
    Diversification of the development of models and algorithms can be based on; different methods
of construction (synthesis) of neural net model solutions; different methods of their training and
retraining; diverse datasets, etc.

    4.2. Models for assessing two-version AI systems

        4.2.1. Theoretical-set model

   Let’s consider two channel AI system that work according to principle “1 out of 2”. Both channels
are equipped by embedded testing means that check up/down states of hardware and software
components. If the channels have been implemented using the same version Va of AI (for example
identical artificial neural networks), sets of input data both channels are described by the formula:
                                   IDva = IDvao U IDvau U IDvas ,                                   (2)
   where IDvao is a subset of input data (ID) on which both AI channels using one version work
correctly; IDvau is a subset of input data on which work of both AI channels is uncertainty; IDvas is
a subset of input data on which both AI channels can work unsafely.
   If the channels have been developed by use of two different versions (with different structure of
neural networks or different techniques and datasets for learning and so on [31]), a set of input data
can be divided into the following subsets:
   • input data of correct behavior of the AI versions Va (a set of input data IDvao) and Vb (a set
       of input data IDvbo);
   • input data (ID) of correct behavior both AI versions Va and Vb described by set
                                        IDvabo = IDvao Ո IDvbo;                                     (3)
   • ID of correct behavior of the AI versions Va or Vb only described by two subsets
                                      IDvao\ = IDvao \ IDvabo,                                  (4)
                                       IDvbo\ = IDvbo \ IDvabo;                                 (5)
   • ID of uncertain behavior of AI versions Va (a set of input data IDvau) and Vb (a set of input
       data IDvbu);
   • ID of uncertain behavior both AI versions Va and Vb described by set
                                     IDvabu = IDvau Ո IDvbu;                                    (6)
   • ID of uncertain behavior of the AI versions Va or Vb only described by two subsets
                                      IDvau\ = IDvau \ IDvabu,                                  (7)
                                       IDvbu\ = IDvbu \ IDvabu;                                 (8)
   • ID of unsafe behavior of AI versions Va (set of ID, IDvas) and Vb (set of ID, IDvbs);
   • ID of unsafe behavior both AI versions Va and Vb described by set
                                         IDvabs = IDvas Ո IDvbs;                                (9)
   • ID of unsafe behavior of the AI version Va or version Vb only described by two sets
                                        IDvas\ = IDvas \ IDvabs,                               (10)
                                         IDvbs\ = IDvbs \ IDvabs.                              (11)
   Сombinations of uncertain and unsafe states of versions are not anlysed, because such cases are
identified as an unsafe (set IDvabs). Note, that sets IDvao and IDvbo are defined by datasets that
were used for learning and are expected for versions Va and Vb.

        4.2.2. Probabilistic models

   Let’s develop probabilistic models of one- and two-version two channel AI-systems. Assumptions
for these models are the following: failure of the checking and reconfiguration means is failure of
AI-systems; failures of the versions (SW and HW) are independent; switching on/off the channels in
case of their failures is carried out instantly.
   Dependency of trustworthy work probability for two-channel (duplicated) one-version AI system
on the probabilities of states can be calculated using the following formula:
                               PAI1 = [P0 + (1 – P0) PD ] (1 – PU1 – PS1) PR1,                       (12)
   where: P0 is a probability of the channel up-state; PU1 is a probability that at the inputs there will
be data from the set IDvau, which will lead to the transition of the channels and AI system to an
uncertain state; PS1 is a probability that at the inputs there will be data from the set IDvas, which
will lead to the transition of the channels and AI system to an unsafe state; PR1 is a probability of the
checking and reconfiguration means for one-version two-channel AI system.
   This indicator for two-channel and two-version AI system is determined as follows:
                              PAI2 = [P0 + (1 – P0) PD ] (1 – PU2 – PS2) PR2,                        (13)
   where: PU2 is a probability that at the inputs there will be data from the set IDvabu, which will
lead to the transition of the channels and AI system to an uncertain state; PS2 is a probability that at
the inputs there will be data from the set IDvabs, which will lead to the transition of the channels
and AI system to an unsafe state; PR1 is a probability of the checking and reconfiguration means for
two-version two-channel AI system.
   Sure that PU2 < PU1 , PS2 < PS1 , PR1 > PR2. Let’s calculate
                δPAI2/AI1 = PAI2 / PAI1 = [(1 – PU2 – PS2) / (1 – PU1 – PS1)] PR2 / PR1 ≈
                              [(1 – βU2 – βS2) / (1 – βU1 – βS1)] PR2 / PR1,                         (14)
   where: βU1 = Card IDvau / Card IDva , βS1 = Card IDvas / Card IDva are coefficients (metrics)
evaluating relative parts of input data which will lead to the transition of the channels and one-
version AI system to uncertain and unsafe states correspondingly;
βU2 = Card IDvabu / Card IDva, βS2 = Card IDvabs / Card IDva are coefficients (metrics)
evaluating relative parts of input data which will lead to the transition of the channels and two-
version AI system to uncertain and unsafe states correspondingly.
   If assume that PR1 ≈ PR2, formula (13) will be the following:
                              δPAI2/AI1 ≈ (1 – βU2 – βS2) / (1 – βU1 – βS1),                         (15)
                       δQAI1/AI2 = (1 - PAI )/ (1 - PAI2) ≈ (βU1 + βS1) / (βU2 + βS2).               (16)
   If part of uncertain and unsafe input data IDvau and IDvas for version of one-version AI system
equals O.1 and part of uncertain and unsafe input data IDvabu and IDvabs for versions of two-version
AI system equals O.02, risk (probability) of unsafe or potentially unsafe states will be decreased in 5
times.
   It should be noted that the presented analytical models for calculating relevant indicators do not
take into account other types of diversity and corresponding faults that can lead to system failures.
AI systems are SW-HW solutions, and therefore, like any system with software or programmable
hardware means, they are subject to design faults caused by developer errors, imperfection of the
technical specifications and so on.
   To tolerate their consequences, the principle of diversity is applied, but it refers purely to the use
of different programming languages and technologies, hardware and software platforms, etc. [31,
32]. Note, that such diversity does not tolerate the specific problems of using AI models, which were
discussed above. This is confirmed by the experience of using the driverless automotive systems [33],
where diversity is actually used to protect against software (design) faults and certain HW (physical)
faults, which in its absence can cause Common Cause Failures (CCFs) of redundant structures.
However, such HW-SW diversity does not protect AI systems against vulnerabilities and complex
kinds of CCFs caused by uncertainty of model behavior, and provide a trust guarantee of safe
functioning.
   Let’s analyze models for one and two model-version AI-systems with one- and two-version SW
(systems AI1-1, AI1-2, AI2-1, AI2-2, where first digital describes number of model versions, second
one is number of SW versions) considering reliability of SW. The following formulas describe
probabilities of up-states of these systems:
                               PAI1-1 = [PHW + (1 – PHW) PD ] (1 – PU1 – PS1) PSWPR1,                (17)
                             PAI1-2 = [PHWPSWr + (1 – PHWPSWr) PD ] (1 – PU1 – PS1) PSWaPR1,         (18)
                               PAI2-1 = [PHW + (1 – PHW) PD ] (1 – PU2 – PS2) PSWPR2,                (19)
                              PAI2-2 = [PHWPSWr + (1 – PHWPSWr) PD ] (1 – PU2 – PS2) PSWaPR2 ,       (20)
   where (in case of independency of failures of HW and SW components of the channels): P0 = PHW
PSW; PHW and PSW are probabilities of the HW and SW up-states; PSW = PSWr PSWa, PSWr and PSWa are
probabilities of the SW up-state considering relative and absolute faults.
   Hence, taking into account expressions (12-15, 17-20) and the insignificant difference in the
probabilities of up-state the checking and reconfiguration means for the systems, the following
formulas for calculating their relative differences can be given:
                  δPAI1-2/AI1-1 = PSWr [PHWPSWr + (1 – PHWPSWr) PD ] / [PHW + (1 – PHW) PD ],        (21)
                     δPAI2-2/AI1-2 = (1 – PU2 – PS2) / (1 – PU1 – PS1) ≈
                               (1 – βU2 – βS2) / (1 – βU1 – βS1),                                    (22)
                δPAI2-2/AI2-1 = PSWr [PHWPSWr + (1 – PHWPSWr) PD ] / [PHW + (1 – PHW) PD ].          (23)
    These expressions allow specifying impact of diversity on the two levels and formulating
requirements to AI versions. Formula (22) describes a simple linear dependency of AI2-2 system
benefits in comparison with AI2-1. Formula (23) is traditional for evaluation of increasing safety due
to using diversity in duplicated systems.

5. Discussion
    5.1. VNP for AI systems: way to immortality

   The VNP began its path of implementation on simple relay and then electronic devices.. Now,
after 60 years, we have come (we are approaching) to the synthesis of reliable (trustworthy...) AI
from insufficiently reliable (trustworthy) components. John von Neumann wrote about reliable
organisms, not about conventional technical systems. He tried to expand the scope of research and
consider bio-technical systems as certain heterogeneous formations. Perhaps the next his step would
be related to purely biological systems and the ideas of redundancy and reconfiguration would be
extended to them.
    Considering the presence of a large number of AI quality characteristics, it is necessary to
consider the possibilities of building “better” systems from the “worst” components separately for
each of the characteristics. So, within the framework of this article, we got closer to artificial
formations ("a little bit of organisms", since AI is a step in this direction) and then it remains to take
the next step to reliable "organisms".
    That is, we can conclude that, firstly, the VPN circle closes, so to speak, in the sense of
"organisms", and the introduction of artificial intelligence, consideration of its dual nature as an
object and a means of ensuring reliability is a way to create and research such reliable organisms.
The transfer of AI to a new technological base, such as creating a bio-technical system, can be
exemplified by the development of the Australian startup, Cortical Labs [34]. They are working on
a new type of artificial intelligence that combines lab-grown human brain cells with computer chips.
This approach further bridges the gap between AI and humans, potentially increasing the level of
the various threats.
    Secondly, a reliable organism made of insufficiently reliable components is a step to immortality!
The path to it can be made both by reserving biological components and by replacing them with
artificial means. As noted in [35], there are two threats to the problem of AI immortality. On the one
hand, it is the possible loss of renewal that is a consequence of death, which can create the risk of
weakening future generations and possible conflicts between them. On the other hand, AI
immortality could create an "artificial intelligence-human" relationship similar to a "god-mortal"
relationship. But in the context of this study, it is about immortality in view of the various types of
failures of AI systems and the possible embedding of components to continue functioning.
    Thirdly, since it is about how to build an organism with a specified value of reliability that is
assessed by probability of up-state for a required time, a person can get a tool to check and control
this level. Therefore, this person, which may also be a mean of artificial intelligence, will have
multiple strategies for ensuring reliability through proactive repair, redundancy and reconfiguration
to provide way to immortality.

    5.2. Features and limitations of applying diversity for proving VNP to ensure
         AI trustworthiness

    Despite the fact that such specific characteristics of AI as trustworthiness, explainability, ethics
are top for intelligent systems, the characteristics of reliability, security and resilience are more
understandable and familiar for developers and customers. This article did not have the task of
delving deeply into the safety and security problems of AI, but they should always be close to the
problems of evaluating and ensuring the necessary level of specific characteristics of AI, first of all,
trustworthiness and explainability. The issue of determining qualitative, and especially quantitative,
requirements for these characteristics is quite complex.
    The principle of diversity can be quite effective from the point of view of as safety and
trustworthiness. Regarding the well-known sub-characteristics of security, namely integrity,
confidentiality and accessibility, the situation is somewhat more complicated, since application of
diversity increases integrity and accessibility measures but can create risks for confidentiality
considering the rule of “weak link”. Therefore, for a more thorough analysis and evaluation, it is
necessary to consider one more the third level in addition to the characteristics and sub-
characteristics.
    Complex and contradictory is the question of the expediency of using the diversity principle for
increasing ethical and lawfulness indicators. Table 2 provides a conclusion about the
inappropriateness of using VNP to improve ethical indicators and notes that VR can be applied if the
versions will provide different reactions on so called situations with ethically unacceptable
alternatives (SEUA). It is theoretically possible to build versions in which such situations will be
diversified to provide reducing the risk of SEUA for a common reason. The practical implementation
of such a principle, for example, for driverless cars, requires the careful specification of the list of
SEUAs, and the development of several AI versions using diversified techniques. Such an opportunity
and ways of its implementation are quite complex and interesting for future research.

6. Conclusion and future work
The main contribution of this study is a framework for the formal presentation of VNP and its
application in intelligent systems and methods of its implementation to ensure trustworthiness and
other specific characteristics of AI. The importance of the proposed models and methods is that they
can be detailed and developed to evaluate the feasibility and ways of using VNP methodology in
creating trustworthy and safe AI systems.
    However, in our opinion, the AI safe/secureware engineering has to be separated as an
independent branch of intelligent engineering. It is fully justified in view of the uncertainty, threats
and risks associated with the use of AI systems in critical domains and impact on consequences
caused by failed/unpredictable behavior.
    Diversity is a really important and promising principle that can be used to provide key
trustworthiness, sаfety and security characteristics of AI systems. This applies to all elements of the
triad AIaXO-AIaXP-AIaXA and scenarios of its implementation.
    Future investigation could be connected with development of detailed models, methods and tools
for assessing and providing specific characteristics and sub-characteristics of AI and AI systems.
These steps should be added by enhancing and developing regulation requirements and justification
of quantitative values for them.

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