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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Method of Improving the Information Security of Virtual Communities in Social Networking Services</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Head of the Information Protection</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Cybersecurity Department of Korolyov Zhytomyr</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Head of educational and scientific center of IT, Zhytomyr National Agroecological University</institution>
          ,
          <addr-line>Zhytomyr</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Lviv Polytechnic National University</institution>
          ,
          <addr-line>Lviv</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Military Institute</institution>
          ,
          <addr-line>Zhytomyr</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Today, social networking services have become one of the most powerful means of mass communication between their users - actors. Social networking services are increasingly acting not only as a mean for the content exchange in the virtual environment, but also as a mean for self-organization of citizens in their real life. Therefore, on the one hand, social networking services are an objective reality of modern life, on the other hand, as the experience of many countries of the world and, first of all, Ukraine shows, is a source of threats to its information security. For example, the result of unfriendly information operations in social networking services is the manipulation of public opinion, the spread of appeals that accentuate international, interreligious and interethnic conflicts, provoke terrorism, separatism and other manifestations of violence and crimes against humanity, peace and security. The article reveals one of the methods of countering such threats. The core method is to increase the information stability of virtual communities in social networking services to destructive information influences through their hidden artificially controlled formation. The formation of information resistant virtual communities is suggested to be carried out on the basis of the critical mass principle. This approach, firstly, provides their further stable development (artificially controlled hidden increase in the number of participants) and, secondly, guarantees critical perception of the content of destructive matter. In addition, for those virtual communities that have unsatisfactory quality performance indicators, it is offered to use latent synergistic management in the form of directed information influence. The accuracy of the developed method has been proved experimentally. As a result of the study, it is found that the information stability of virtual communities in social networking services at the time of using the suggested method is higher in comparison with the natural uncontrolled processes of their creation.</p>
      </abstract>
      <kwd-group>
        <kwd>social networking service</kwd>
        <kwd>virtual community</kwd>
        <kwd>actor</kwd>
        <kwd>information security</kwd>
        <kwd>method</kwd>
        <kwd>information stability</kwd>
        <kwd>synergetic management</kwd>
        <kwd>critical mass</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>Introduction</title>
      <p>Despite the diversification of communication channels, social Internet services
(SNSs) have become the most popular segment of mass communication. At present,
SNSs not only consolidate the tools for messaging and multimedia content, but also
apply for the self-organization of society into virtual communities and the realization
of interactions in real life. The growing popularity of SNSs is inextricably linked with
the emergence of State Information Security (SIS) challenges in the information space
of virtual communities. So that, SNSs are actively used by the Russian Federation to
conduct a hybrid war against Ukraine. Such a form of confrontation is carried out by
combining technologies of cyber impact on critical infrastructure objects and
informational impact on citizens in the information space, in particular, in SNSs. The purpose
of performing the information influence on the SNSs actors by the opposing party is
to manipulate the personality, group of people and masses, disseminate
misinformation to influence social and political processes in the state, spread chaos among the
population, etc.</p>
      <p>
        According to data [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] in 2018, the US Department of Justice has accused a Russian
citizen of attempting to interfere with the US political system, in the midterm
elections that has taken place in November. Such an intervention has been carried out
using SNSs to discuss such issues as immigration, control and possession of weapons,
racial relations, LGBT and women’s rights march. The attackers have appeared to be
American political activists, creating thousands of fake accounts in SNSs. The
objectives of such actions have been polarization and the spread of antagonism in
American society based on social and inter-racial contradictions, erosion of democracy and
limiting the rights and freedoms of citizens.
      </p>
      <p>
        Taking into account the growing level of threats to the national security of the world’s
leading countries as a result of the destructive influence of threats to information
security, the European Parliament has accepted a resolution with recommendations to
the EU Council and EU diplomacy focused on countering the propaganda “from
Russia’s side and other hostile actors” [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. The European Parliament has recommended
“to raise awareness about Russia’s disinformation campaigns,” which, according to
the parliamentarian, is “the main source of misinformation in Europe.” The European
Parliament offers to develop a “legal framework, both at the union level and
internationally, to counter hybrid threats, cyberwar and information war” [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ].
Therefore, there is an objective contradiction between the problem of the practice of
ensuring the sustainable development of the SNSs information space in the conditions
of its globalization, and the increasing number of threats to the SNSs and the problem
of science in developing effective approaches to counteract such threats, which
guarantee a reduction of the level of destructive information influence on the SNSs actors.
2
      </p>
    </sec>
    <sec id="sec-2">
      <title>Literature Review</title>
      <p>
        Numerous studies of the specific use of SNSs actors for communicating on the
Internet [
        <xref ref-type="bibr" rid="ref3 ref4 ref5 ref6">3-6</xref>
        ] define them as a tool for the formation of a dynamic information space. In
turn, SNSs provide actors with the means of representing their identity in the virtual
space and the tools for creating different types of relationships with other actors
(friends, followers, members of virtual communities, etc.). Among the basic SNSs
functions, the following publications are highlighted [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]: management of the
identification of actors to meet the needs for referring to a selected category of users and
setting access rights to the profile; search of experts by means of proactive
recommendation of relevant SNSs actors based on the given criteria - surname, interests,
sphere of activity, etc.; contact management, which involves the functionality of
interaction with a certain set of actors, in particular limiting access to the profile,
designating actors in posts and content of different types; awareness of the actors’ activity
in SNSs includes tracking content publications, events in the lives of actors, events,
participation in virtual communities; exchange of content between actors in SNSs
with the use of direct and indirect means. While the direct exchange, there is a
communication with the addressing of the content to the specifically defined actor.
Indirect exchange includes the publication of photo and video content, the creation of
public events and postings.
      </p>
      <p>
        It is known that structurally SNSs represent a network of crosspoints – actors, which
are linked by relationships – connections. Considering the peculiarities of the
processes of interaction between actors, it is appropriate to describe SNSs as a complex
nonlinear dynamic system [
        <xref ref-type="bibr" rid="ref7 ref8">7, 8</xref>
        ]. In the case of attack to the SIS in SNSs, the
interaction of actors goes into chaotic dynamics, it becomes unpredictable and uncontrolled
not only in the virtual space, but also in the real life of a society [
        <xref ref-type="bibr" rid="ref10 ref9">9, 10</xref>
        ]. The
publications [
        <xref ref-type="bibr" rid="ref11 ref12 ref13">11-13</xref>
        ] show that the effective direction of threats’ counteraction to the SIS in
SNSs is the use of synergistic management. The main point of such management is to
spread the content of directed matter in the information space of SNSs, and as a result
of this influence, the processes of self-organizing actors happen. As a result, the
indicators of the actors’ interaction in SNSs, in particular the demand for content of
destructive matter, reach the desired values, and the virtual community moves to a stable
predetermined state of the information security. However, such studies are aimed at
the SIS operational counteraction of threats in the information space of SNSs under
the dynamic confrontation conditions. The task of forming the structures of actors’
virtual communities, that are resistant to destructive information influences in SNSs,
remains unresolved. This approach will allow to reduce the cost of resources for
stable monitoring of SNSs information space and counteraction of threats to the SIS.
The analysis of academic research in the direction of artificially managed synthesis of
stable structures of virtual communities in SNSs has shown that this issue has not
been studied sufficiently [
        <xref ref-type="bibr" rid="ref14">14-16</xref>
        ]. The explicit direction of research is inextricably
linked with the use of the virtual community’s startup approach in SNSs. It is
established that to the basic conditions for a successful startup of the virtual community in
SNSs, which can be considered sufficient, it is appropriate to refer the following [17,
18]: the correct community’s preparation for promotion; maintaining a stable number
of actors who enter the community for a specified period of time; obligatory retention
of the 10% barrier of the carriers’ ideas of the virtual community; timely placement of
high-quality content; the choice of rational ways of distributing content about the
community, etc. At the same time, the success of the startup depends on whether the
virtual community gains a sufficient number of actors, that is, such a critical mass,
which will be sufficient for its further self-development. Therefore, this condition can
be attributed to the category of necessary ones, compliance of which is obligatory for
the startup of all virtual communities in SNSs.
      </p>
      <p>
        Also, from the literature analysis on the study’s topic [19-23] it has been established
that the problem of the virtual community’s startup in SNSs on the critical mass
principle has not been worked out either theoretically or methodically until today. The
vast majority of studies [
        <xref ref-type="bibr" rid="ref7">7, 20-22</xref>
        ], etc., focus on mastering the issues of developing,
researching and analyzing the SNSs models. Also, in a number of scientific
publications [
        <xref ref-type="bibr" rid="ref3 ref4 ref5 ref6">3-6</xref>
        ] and others, attention is focused on the study of issues related to the social
and humanitarian role of SNSs in the life of civil society.
      </p>
      <p>Thus, the task of increasing the information stability of virtual communities in SNSs
to destructive information influence by combining the approaches of the virtual
community’s startup in SNSs and the synergistic management of interaction between
actors is a burning strand of the research.
3
3.1</p>
    </sec>
    <sec id="sec-3">
      <title>Materials and Methods</title>
      <sec id="sec-3-1">
        <title>Virtual Communities as Complex Dynamic Systems</title>
        <p>
          Virtual communities in SNSs represent an association of actors that interact with each
other to implement interpersonal and group communication in the information space
[25]. As a result of such interaction, virtual community actors in SNSs create their
own informational content. In turn, structurally, virtual communities in SNSs consist
of a large number of actors and is a complex dynamic system with vertical and
horizontal links between them. Therefore, in Fig. [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ] we demonstrate the virtual
community in SNSs as an unoriented graph.
In fig. [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ] actors in SNSs are marked with circles, and the interrelationships between
them – with three types of lines: the solid line is used to represent stable relationships
that ensure the cooperation of information interaction under the influence of external
factors of the information space and remain unchanged (for example, friendship
between actors); solid lines with arrows at the end point to flexible links between actors
that are capable of responding instantly to changes in the information space
parameters and are usually unidirectional (followers, etc.); weak links are marked by a
dashand-dot line and are characterized by significantly limited information interaction due
to an inadequate level of common interests between actors.
        </p>
        <p>Also, the figure shows two types of actors in SNSs. The first group of actors is
represented by a solid circle – they are part of the virtual communities and interact with
other actors in them; the second group is marked by a dual circle – these users do not
belong to virtual communities, but they can monitor their activity. As a result of the
attack to the SIS in SNSs, the interaction of actors becomes unregulated and
uncontrolled, which leads to the emergence of chaotic dynamics. Signs of chaotic dynamics
of actors’ interaction processes in SNSs are:
 appearance of high sensitivity to the initial conditions that characterize the
information space;
 fractal motion marks of the depicting point in the system’s phase space;
 the increasing complexity of establishing links between actors and virtual
communities as a result of changing some of the parameters of the SNSs information
space;
 the transitional chaotic reactions of actors and virtual communities to distributed
content, non-periodic bursting of the content publication of destructive matter, or
the irregularity of the distribution of such content from the moment it is thrown
into the information space.</p>
        <p>Therefore, the functioning peculiarities of virtual communities’ actors in SNSs in the
conditions of carrying out destructive information influence cause a conceptual
problem, the solution of which is aimed at reducing the level of information entropy in the
system in order to stabilize the actors’ public opinion, increase their level of critical
perception of misinformation and, finally, regularization of interconnections between
members of the community and the decisions they make.
3.2</p>
      </sec>
      <sec id="sec-3-2">
        <title>Information Stability of Virtual Communities in SNSs</title>
        <p>
          It is known that in the broad sense, the immunity of social communities is the ability
to use their own resources to respond, to counteract and to continue functioning under
the influence of negative factors [25]. The publications [
          <xref ref-type="bibr" rid="ref11 ref12 ref7 ref9">7, 9, 11, 12</xref>
          ] have proved that
as a result of the attack to the SIS in SNSs, not only the promotion of content of
destructive matter in the information space happens, but also the change in the
relationship between actors and, as a consequence, structures of virtual communities.
Therefore, under the information stability of the virtual community in SNSs, it is
suggested to understand its ability to respond and to recover from the impact of threats to
information security, to adapt to changes in the information space and to realize their
purpose of functioning. The category under consideration differs from the information
security concept of the virtual community considering the requirement for its
sustainable development in the SNSs environment. Under the conditions of information
confrontation with the use of SNSs, intruders use innovative technologies of information
influence on actors and, due to technological advantages and element of surprise, can
successfully achieve their objectives. At the same time, assisting the information
security of virtual communities involves activities aimed at excluding the possibility of
implementing external and internal threats in the SNSs information space [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ].
Consequently, the achievement of the information stability of the virtual community in
SNSs provides preliminary readiness, adequate response and successful recovery to
the given state of the virtual community’s information security after the SNSs threat.
Factors that affect the information stability of virtual communities in SNSs are
presented in Fig. [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ].
The achievement of the SIS in SNSs is possible as a result of the realization of an
effective state policy in the information sphere in accordance with the current
legislation, the use of a complex measures aimed at meeting the contemporary challenges in
the information space and the means of controlling them. The guarantee of the SIS in
SNSs is primarily the responsibility of the relevant departments, which are
determined by the current legislation of the certain state. In particular, the national interests
of Ukraine in the information sphere, the threats to their implementation, the
directions and priorities of state policy in the information sphere are determined by the
Doctrine of Information Security [26].
        </p>
        <p>Social norms in SNSs are represented by a set of generally accepted rules, standards,
relations between actors that provide the sequences of the virtual community, the
stability of the processes of interaction between actors in the context of attacking the
SIS [27]. Social sanctions in SNSs are a set of punishments in the legal field of the
state and the SNSs environment, which are used in the case of detecting deviations
from the generally accepted norms of interaction between actors and virtual
communities in order to meet the respected community standards in the information space of
SNSs [27]. According to the work of Michael Scriven &amp; Richard Paul [28], critical
thinking of actors in SNSs is an intellectual process for the active reflection,
application, analysis, synthesis and / or evaluation of content collected, or generated through
observation, experience, reflection, reasoning or interaction with other actors, which
prompts actions in the information space of SNSs.
3.3</p>
      </sec>
      <sec id="sec-3-3">
        <title>The method of forming the informationally stable virtual communities</title>
        <p>
          We envisage the formation of a stable virtual community using an approach based on
the virtual communities’ startup in SNSs. Considering the results of recent scientific
studies [
          <xref ref-type="bibr" rid="ref3 ref4 ref5 ref6 ref7">3-7</xref>
          ] and experimental using [16, 22, 23], as well as the basic notions of
nuclear physics, we give the following definitions of the critical mass of the virtual
community in SNSs and its start-up:
 the critical mass M
        </p>
        <p>of the virtual community c  C in SNSs g  G is the
minimum number of actors amin  A that are consuming and generating new content
k  K , which provides the activation of the viral (virus) loop v and
selfdevelopment e of the virtual community;
 the virtual community startup in SNSs is a newly created virtual community c  C
in SNSs g  G , which twists under severe resource limitations omin  O ;
 viral loop v means the speed of content distribution between actors a  A of the
virtual community c  C in SNSs g  G ;
 the critical state of the virtual community is the steady state of the virtual
community c  C in SNSs g  G , in which the number of actors aconst  A does not
change in time t T ;
 criticality means the conditions under which the virtual community c  C in SNSs
g  G supports the mechanism of self-development e .</p>
        <p>Taking into account the given definitions it can be confirmed that the problem of the
virtual communities’ startup in SNSs occurs when there is a need for rapid activation
of the loop, which will ensure the self-development of the community under the
conditions of severe resource limitations. But in practice, the solution of this problem
involves solving the contradiction, which is to meet the needs of adjustment the high
requirements that are put forward to the pace of the loop activation of the newly
created virtual community with the involvement of a minimum number of actors, to the
severe resource limitations that are set. So that, solving the discovered contradiction is
suggested on the basis of the critical mass principle.</p>
        <p>Since today there is no common approach for determining the critical mass for the
startup of virtual communities in SNSs, at a first approximation the principle of
critical mass in the formalized form can be described as following
min  M  : a  amin , o  omin ,
(1)
where amin means the minimum number of actors required to provide a successful
startup of the virtual community c in SNSs g , amin  A , c C , g G ; omin
describes the minimum cost of resources that is enough for a successful startup of the
virtual community c in the social network g , omin  O .</p>
        <p>
          In the direct formulation, the task of determining the critical mass of the virtual
community (1) is incorrect [29]. We regularize the principle (1). To do this, we use the
metric of self-similarity – the Hurst index [30, 31]. Unlike the well-known metrics of
self-similarity, the Hurst index will provide not only the trendsetting in the sequence
of filling the virtual community with new actors, but also establish the nature of the
startup. In such a way, the value of the Hurst index H is going indirectly to answer
the question whether the virtual community of critical mass min  M  has reached a
minimum number of actors amin and dedicated resources omin (1) or not, that is
min M   H . In Table [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ], qualitative signs of the startup are defined by the
quantitative values of the Hurst index.
The calculation of Hurst indexes, which will determine the quality category of the
virtual community startup in the social network, is performed according to the
expression
        </p>
        <p>H </p>
        <p>lg  R S 
lg  m  2
,
(2)
where H is the Hurst index; S means average deviation of a number of
observations; R is the dispersion of accumulated deviation; m is the number of observations.
Consequently, adherence to the critical mass principle provides the stable
development of the virtual communities’ dynamics, which in the future excludes the reduction
of the number of their actors, provides the stability of interaction relations between
them, the ability to perform functions of social control. Thus, the startup of virtual
communities in SNSs based on the critical mass principle serves as a guarantee of
increasing their level of information stability.</p>
        <p>
          For a case when the virtual community startup in SNSs according to the data in tab. 1
is characterized by qualitative indicators “unsuccessful” or “accidental”, it is not
capable of independent functioning and development. Achievement of a given level of
information stability by such virtual community is possible only with the constant
hidden information influence on the actors in SNSs. Such security actions require the
use of significant resources – financial, human and technical, etc. Therefore, we
analyze the process of forming a virtual community of actors, which will be capable of
stable self-development by activating the loop in SNSs using synergistic management
[
          <xref ref-type="bibr" rid="ref9">9</xref>
          ].
        </p>
        <p>Considering the high speed of growing the number of actors and virtual communities
in SNSs, the origin of evolutionary processes within the virtual communities, the
intensity of information exchange between SNSs and the external environment of its
functioning – the national and world information spaces, we use the model of
microbiological system for the description of the actors’ interaction in SNSs [32]. At the
same time, the publication of the content of given matter is carried out by members of
the virtual community team in SNSs, acting as its administrators.</p>
        <p>
          Therefore, we formalize the processes of interaction between actors of the virtual
community in SNSs in the form of the Mono model [
          <xref ref-type="bibr" rid="ref13">13, 32, 33</xref>
          ], which is a system of
ordinary differential equations
 dx t 
 dt

 dQ t 
 dt
  Q  x  Dx,
 DQ  Q  x  DQ;
0
(3)
where x t  stands the number of actors in the created virtual community; Q t 
describes a part of team members’ publications in the virtual community; Q0 means a
part of new publications on a given topic in the virtual community, published by team
members; D indicates the speed of new members’ appearing of the virtual
community in the absence of artificial influence on actors;  1 indicates the coefficient, which
specifies a part of publications on a given topic, which has influenced the formation
of public opinion of the virtual community actors;  Q x means the increase in the
number of actors in the virtual community due to the impact of published content by
team members,  Q   zQ ; Dx stands the reducing the number of virtual
kz  q
community actors;  Q x stands the number of publications that has influenced
the formation of public opinion of virtual community actors; DQ0 describes the
intensity of publications that has caused interest in actors of SNSs and has encouraged
them to become participants in the virtual community; DQ means the intensity of
publications that hasn’t caused interest in actors of SNSs and hasn’t encouraged them
to become participants in the virtual community.
        </p>
        <p>Limitation 1. The growth rate of a virtual community’s participants depends only on
the part of team members' publications in the virtual community.</p>
        <p>Limitation 2. The participants’ publications of a virtual community team are
distinguished by content, form of material feed, content type, but are joined together by a
common narrative, which must be get across to actors in direct or latent form to
influence their public opinion.</p>
        <p>We perform the synthesis of such synergetic management u t  , which will provide
the formation of a virtual community of actors in SNSs, capable of further sustainable
functioning with the aim of spreading and promoting a strategic narrative aimed at
counteracting destructive information influence. Then the system of differential
equations (3) will take the form where the part of new publications on a given topic in the
virtual community, published by the team members Q0 will be specified by the
controlling action u t 
 dx t 

 dt

 dQ t 
 dt</p>
        <p>
          Artificially controlled self-organization of actors in SNSs in the virtual community
will be achieved through the entry of a dynamic invariant into the system (3). The
chosen dynamic invariant should consider the peculiarities of the processes of actors’
social communication in SNSs. From the studies [
          <xref ref-type="bibr" rid="ref8">8, 34</xref>
          ] it is known that the increase
in the number of actors of the virtual community at a certain stage of its development
is slowed down and asymptotically reaches the boundary level. It is rational to
formalize this phenomenon in the form of a differential equation of logistic type
dx t 
dt
The physical content of the function  t  is to reduce the need for the content of the
specified matter to be provided by the members of the virtual community of SNSs
 Q by increasing the number of the virtual community members to the critical

level [35] in accordance with the expression  xsup 1

x 
 and the speed of the new

xsup 
members’ appearing in the virtual community D .
        </p>
        <p>
          According to [
          <xref ref-type="bibr" rid="ref11 ref13">11, 13</xref>
          ] expression (6) must satisfy the functional equation
where  stands the parameter that determines the desired rate of increasing the
number of the virtual community actors; xsup indicates the limited number of participants
in the virtual community at the stage of its development.
        </p>
        <p>
          The use of the model (5) to describe the processes of creating a virtual community in
SNSs provides the visibility of their demonstration, in comparison with other models
of logistic type, presented in publications [
          <xref ref-type="bibr" rid="ref11 ref12 ref13">11-13</xref>
          ].
        </p>
        <p>
          Consequently, in accordance with the concept of synergistic management of the
actors’ interaction in SNSs, suggested in [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ], and taking into account (5), the parameter
of the system’s order is its attractor, to which all the phase trajectories of the
controlled system (4) will follow, takes this form
(6)
(7)
(8)
T
d t 
dt
        </p>
        <p> t   0 ,
where stands the time during which a synergically controlled virtual community will
have transient processes to a given state of the SIS in SNSs.</p>
        <p>The substitution of the attractor’s model (6) in the differential equation (7),
considering the system (4), allows us to specify the analytical form of the model of synergetic
management</p>
        <p>Du t    x Q  DQ 
kz  Q2
 zQ</p>
        <p> x Q   Dx 
1 
  Q    xsup 1</p>
        <p>T 
x  </p>
        <p>  D 
xsup  
In order to achieve a stable state by the current virtual community in SNSs, we will
perform a study of the system of differential equations (4) on the stability using the
Lyapunov’s function method [36]. For the number of actors in the virtual community
in SNSs 0  x  1 the derivative from the Lyapunov’s function V   0 , if xsup  1
where   D , when   0 and D  0 . In the case xsup  1 of system (4) is stable
where   0 and D  0 or   0 and D  0 . In the same way, other conditions of
the system’s stability (4) are specified.</p>
        <p>
          As a result of the synergistic management’s influence (7), the processes of actors’
self-organization will be started in SNSs, and after a while the system will reach the
point of a burst of synergistic effect [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ], in which the virtual community will move
to a steady state. The coordinates of the splash point of the synergistic effect acquire
the following values
        </p>
        <p>
x1  xsup  D  xsup 

1 </p>
        <p>
           ,
 
In Fig. [
          <xref ref-type="bibr" rid="ref3">3</xref>
          ] a BPMN diagram of the worked-out method for improving the information
stability of virtual communities in the Aris environment is presented, and its main
stages are specified.
We will undertake an experimental study of the worked-out method for increasing the
information stability of actors in SNSs on the example of virtual communities c1 and
c2 in SNSs Facebook. The names of virtual communities c1 and c2 are not disclosed
due to their commercial secrecy.
        </p>
        <p>
          As inputs for estimating the critical mass for the startup of virtual communities c1 and
c2 in SNSs Facebook, the experimental data received in 2014 have been used and
presented in Table [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ].
Promotion terms of virtual communities’ actors c1 and c2 are presented in Table [
          <xref ref-type="bibr" rid="ref3">3</xref>
          ].
        </p>
        <p>
          Sufficient conditions for promotion of the virtual community
The correct preparation of the virtual community for promotion
Keeping a stable number of actors entering the virtual community
for a specific period of time
Obligatory keeping of the 10% barrier to the idea of a virtual
community
Timely publication of high-quality content
Choosing rational ways to spread information about the virtual
community
c1
+
+
–
–
+
Virtual community
Calculation of the corresponding metrics of self-similarity (2) for virtual communities
c1 and c2 has been carried out according to a well-known method [30, 31]. Results of
R/S-analysis of the virtual communities’ functioning is presented in Fig. [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] (a), (b).
The analysis of the obtained results allow us to draw the following conclusions:
1. the values of Hurst indexes for virtual communities c1 and c2 are HC1  0.487 and
HC2  0.653 accordingly. In Fig. [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] the corresponding values of the indexes HC1
and HC2 are indexes of degree in the equations of approximation;
2. comparison of the obtained results with the data of Table [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ] shows that for
resource omin  28 days that is dedicated to the creation of virtual communities,
virtual community c1 has no critical mass min  M  . The Hurst index for this
community characterizes the process of filling it with new actors, as a process of
random nature.
In the second case - for a virtual community c2 , the obtained results allow to
approve that the startup is successfully hold. The process of filling the virtual
community c2 with an accuracy of 99.73% is persistent, that is, it has signs of a trend.
Thus, the critical mass min  M  for a given virtual community for certain
conditions will reach amin  1274 actors. As a result of the successful creation of the
virtual community c2 in SNSs Facebook on the critical mass principle min  M  (1),
(2) the activation of the virtual loop v has been provided and the mechanism of
self-development e has been launched. The adduced conclusion is confirmed by
the practice, as of 11/18/2014 as a result of the launch of the virtual community’s
c2 self-development mechanism e on the principle of critical mass min  M  , the
number of actors in it is 2211. As a result, this virtual community becomes resistant
to destructive information influence, is able to perceive such content critically, uses
in its activity the mechanisms of social control and social norms to neutralize the
threats to the SIS in SNSs. Also, an additional factor that increases the information
stability of the virtual community is the state actors’ actions to provide SIS.
Consequently, to manage the processes of creating a virtual community c1 , in which
the self-development mechanism has not been launched due to the use of the critical
mass principle, we apply synthetic synergistic management (8). In this case, the
parameters of a controlled system of differential equations (4) acquire the following
values  z  0, 5 , kz  0,5 ,   0, 3. The speed of the appearing of the virtual
community’s new members in the absence of artificial influence, we define as the
coefficient of linear regression equation for a number of data of the total number of actors
in Table [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ], which comes to the fore D  0, 031103 actors / day. The duration of
transitions in a synergetically controlled virtual community T  1 day. Initial number
of actors in the virtual community x 0  0, 008103 , a part of team members’
publications in the virtual community Q 0  2% . Let the desirable growth rate in the
number of virtual community actors figures up to   0, 05 103 actors per day, and
the limited number of actors in the community at the stage of its development is –
xsup  5103 actors. Then, the modeled results of the synergistic impact on the virtual
community will look like as in Fig. [
          <xref ref-type="bibr" rid="ref5">5</xref>
          ], and a change in the part of publications of
team members in a controlled virtual community – in Fig. [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ].
        </p>
        <p>
          Fig. 5. The number of virtual communities in SNSs, 103 actors: a synergetically controlled
process of formation x t  ; an uncontrolled process of formation xexp t 
The data analysis in Fig. [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] shows that in the case of a synergically controlled
information impact on virtual community actors in SNSs, their number over the period of
t  40 days increases to 3,17 103 . In this case, in the absence of such influence in
t  28 days after the experimental data, the number of actors will equal 0,812 103 ,
and with its use – 2,843 103 . It should be noted that the synergistically controlled
information impact on the actors of the investigated virtual community in the early
stages t 0;15 provides a lower rate of growth in the number of participants and is
a bit inert. However, at the next stages, t 16; 40 the process of attracting new
actors is much more intense. At the same time, the part of the team members'
publications in the virtual community in SNSs Q t  on the first day is 28% and gradually
decreases to 2.2% in t  40 days. The virtual community that is being synthesized
will independently distribute multimedia content with a specified narrative, which
will counteract the threats to the SIS in SNSs.
        </p>
        <p>Consequently, the effectiveness of synergetically controlled information influence on
virtual community actors in SNSs increases in 3,5 times in comparison with the
natural processes of their creation, and the virtual community formed in such a way is
capable of further self-development through self-organization processes and
informationally sustainable against the impact of IS threats.
5</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Conclusions</title>
      <p>For the first time, to provide the SIS in SNSs, a method for increasing the information
stability of virtual communities is worked out, based on a combination of the critical
mass principle and the principle of synergistic management of the actors’ interaction.
At the same time, the information stability of the virtual community in SNSs is
reduced to the ability of responding and recovering after the impact of threats to
information security, adapting to changes in the information space and realizing their
purpose of functioning. It is proved that adherence to the critical mass principle provides
stable development of the virtual communities’ dynamics and their information
stability, which in the future excludes the reduction in the number of their actors and
provides further self-development. For virtual communities that are characterized by
unsatisfactory qualitative indexes of the startup, the self-organization of actors in
SNSs is due to the influence of synergistic management. In such a virtual community
there are coherent collective processes and the directed self-organization of the
community and the parameters of interaction processes between actors. Such a virtual
community is informationally resistant to the impact of threats to the SIS in the
information space of SNSs. In the future it is planned to investigate the influence of the
promotion conditions of the virtual community in SNSs to its critical mass.
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