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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>May</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>The Algorithm and Software for Selection of Optimal Topology of Information Systems with Limited Budget</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Andriy Makarchuk</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Oleg Barabash</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Oleh Kopiika</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Volodymyr Tkachov</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Bohdan Bilyavskiy</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Institute of Applied Control Systems of the National Academy of Sciences of Ukraine</institution>
          ,
          <addr-line>Akademika Glushkova Ave. 40, Kyiv, 03187</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”</institution>
          ,
          <addr-line>Beresteiskyi Prosp. 37, Kyiv, 03056</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>The National Defence University of Ukraine</institution>
          ,
          <addr-line>Air Force Avenue, 28, Kyiv, 03049</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2025</year>
      </pub-date>
      <volume>1</volume>
      <fpage>3</fpage>
      <lpage>14</lpage>
      <abstract>
        <p>In the context of rapid advances in information technology, there is an increasing demand for the development of efficient, scalable, and resilient network infrastructures that integrate distributed computing modules or autonomous devices into a cohesive system. Such a need is particularly pronounced in fields that require high levels of automation, fault tolerance, and adaptability - including telecommunications, cloud computing, decision support systems, healthcare information networks, banking infrastructure, and nextgeneration energy grids. When the availability of financial and physical resources is limited, a major challenge arises: not only must the network successfully interconnect all its components, but it must also guarantee maximum functional stability under a constrained total budget and varying costs for establishing individual communication links. This paper proposes a novel method for constructing an optimal node connection topology represented as an undirected graph, with a specific focus on maximizing the network's robustness under cost constraints. The proposed model formalizes functional stability using a functional stability indicator. An optimization algorithm is developed to identify the most resilient network configuration - one that minimizes the risk of fragmentation or failure due to the loss of specific links or nodes. A key component of the model is the integration of edge weights representing individual link costs, alongside a global budget constraint enforced as part of the optimization objective. Furthermore, the study introduces a software prototype that implements the developed algorithm. The tool provides an automated mechanism for generating optimal network topologies, alongside features for visualizing the resulting structure. The results presented in this work may be directly applied in the design and deployment of intelligent distributed systems that demand high resilience and adaptability, ensuring robust performance in realworld operational environments.</p>
      </abstract>
      <kwd-group>
        <kwd>1 Optimization</kwd>
        <kwd>computer network</kwd>
        <kwd>functional stability</kwd>
        <kwd>distributed systems</kwd>
        <kwd>topology</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>The use of various networks is a popular approach for solving tasks in many fields [1-3].
However, to utilize these networks effectively, it is necessary to establish connections between
multiple machines (modules, sub-networks, etc.). Naturally, real-world tasks require considering
various factors such as connection time, cost, and other constraints. Given the need for highly
reliable networks while adhering to budget limitations, it would be beneficial to have an algorithm
that generates an optimal connection topology – one that maximizes functional stability [4-6] while
staying within a given budget.</p>
      <p>This problem can be formulated as a graph enumeration or traversal task [4, 5, 7]. However,
many existing graph-based algorithms either provide only partial solutions to this problem or
require excessive computation time. This work proposes a new modification of an exhaustive graph
search algorithm that fully addresses the described problem while significantly reducing the
required computation time.</p>
    </sec>
    <sec id="sec-2">
      <title>2. An algorithm description and analysis</title>
      <p>Optimization of exhaustive graph, described in this work based on two concepts: decreasing of
number of traversed graphs an estimation of indicator of functional stability. After description of
the algorithm it would be good to see how this algorithm works, For automation of this algorithm
authors developed software, what allows to visualize optimal topology of resulting network. Using
developed software it will be shown, that described algorithm may give good optimization of
finding of topology of connections of machines between each other.
2.1.</p>
    </sec>
    <sec id="sec-3">
      <title>Description of a selection algorithm</title>
      <p>
        Let consider, that we have n machines and we want to connect it between each other by
connection lines. In other hand, let consider, that we know general budget B and we have prizes
matrix
where cij is a cost of laying a communication line between machines vi and v j . For estimation of
functional stability of considered information let use indicator R [4], what may be defined as
integral
(
        <xref ref-type="bibr" rid="ref1">1</xref>
        )
where Rij ( p) = Rij is probability of connectivity [4] for pair of vertices (vi , v j ) in case, when
probability of serviceability of all machines and connection lines equals 1 or p .
      </p>
      <p>As we know, selection of topology of the metwork, what is optimal in some sense [8, 9], is
equivalent to the task of selection of (mostly, unordered) graph G = G (V , L), what describes a
topology of information system, with number of vertices equals the number of machines. If we have
criterion of optimality, we may use exhaustive search of graphs to search optimal. But exhaustive
⎛ n(n−1) ⎞
search of graphs in case of graph with n vertices have computational difficulty equals O⎜⎜ 2 2 ⎟⎟ ,
⎝ ⎠
what is very bad variant. This factor is a reason to optimization of exhaustive search of graphs.</p>
      <p>For optimization of exhaustive search of graphs with n vertices let use two ideas. First idea
based on limitation of number of connection lines. To do it let consider sequences: first sequence
(let note it as {λu } ) is a sequence of values cij ,i = 2,3,..., n, j = 1, 2,...,i −1, what are sorted in
descending order and second sequence (let note it as {λu }) is a sequence of values
cij ,i = 2,3,..., n, j = 1, 2,...,i −1, what are sorted in ascending order. Now let consider numbers N and
N , what may be calculated by formulas</p>
      <p>C = cij i, j=1,2,...,n ,</p>
      <p>1
i, j=1,2,...,n ∫0 Rij ( p ) dp,
R = min
i≠ j</p>
      <p>n ⎫
N = max ⎨⎧n : n ∈ • ∧ ∑λu ≤ B⎬,
⎩ u=1 ⎭</p>
      <p>n ⎫
N = max ⎨⎧n : n ∈ • ∧ ∑λu ≤ B⎬.</p>
      <p>⎩ u=1 ⎭</p>
      <p>
        Using purpose, that there is a sense to work only with connected graphs, and numbers N , N ,
we may formulate interval of permissible number of communication lines formula
⎛ n(n −1) ⎞
max (n −1, min ( N, N )) ≤ L ≤ min ⎜ , max ( N, N )⎟, (
        <xref ref-type="bibr" rid="ref2">2</xref>
        )
⎝ 2 ⎠
      </p>
      <p>Second idea of optimization based on approximation of indicator R using regression polynomial
P%3, what is described in [4] and may be written by formula</p>
      <p>
        R ≈ P%3= P%3(η min ,η max , S, qG ,uG ) =
= 7,01ηmin + 2,57ηmax +1,14S −13,69qG − 3,84uG −14η m2in − 4,56ηminηmax + 5,6ηminS −
−21,83η minqG + 7,54η minuG −1,63η m2ax − 2,11η max S − 6,53η maxqG + 7,05η maxuG − 7,96S 2 +
+32,52SqG + 0,19SuG + 35,09qG2 + 4,38qGuG − 2,89uG2 +12,98η m3in −1,66η m2inηmax − 7,23η m2inS +
+12,31η m2inqG + 4,42η m2inuG + 0,72ηminηmax + 7,89ηminηmaxS + 4,66ηminηmaxqG −1,74ηminηmaxuG −
2
−7,23ηminS2 +17,93ηminSqG −13,87ηminSuG + 6,99ηminqG2 − 4,48ηminqGuG − 0,28ηminuG2 −
−0,49η m3ax + 5,21η m2axS + 3,09η m2axqG − 4,03η m2axuG − 5,78ηmaxS2 − 5,6ηmaxSqG −
−7,64ηmaxSuG + 5,09ηmaxqG2 + 3,35ηmaxqGuG + 7,19ηmaxuG2 + 7,22S3 −1,48S2qG +
+13,25S2uG − 50,9SqG2 − 20,74SqGuG + 0,49SuG2 − 24,57qG3 +11,39qG2uG + 0,47qGuG2 − 3,7uG3, (
        <xref ref-type="bibr" rid="ref3">3</xref>
        )
where ηmin = dmin , ηmax = dmax , , qG = κ G , uG = λG ,, dmin is min degree of a graph G , dmax is
n −1 n −1 n −1 n −1
max degree of a graph G , κ G is a degree of vertex connectivity of graph G , λG is degree of edge
connectivity and n is a number of vertices (what represent machines). Using (
        <xref ref-type="bibr" rid="ref2">2</xref>
        ) and (
        <xref ref-type="bibr" rid="ref3">3</xref>
        ) we may
optimize search of optimal topology of considered information system, what is described by
unordered connected graph G or, in other words, we will be able to answer, how to connect n
machines using conditions, described above.
      </p>
    </sec>
    <sec id="sec-4">
      <title>2.2. Examples of usage of described algorithm using its realization in software</title>
      <p>In borders of the study a specialized software was realized. This software realizes described
algorithm for finding optimal way of connection of machines in one information system. To see its
work, let consider two examples.</p>
    </sec>
    <sec id="sec-5">
      <title>2.2.1. First example of usage of described algorithm</title>
      <p>Let purpose, that it’s needed to connect four servers between each other and we know, that
general budget, what is given for connection, equals 10000$ and prizes for laying every connection
line may be represented by matrix</p>
      <p>If we enter these data into the realized software, we will have result like demonstrated on fig. 1.</p>
      <p>As we may see on fig. 1, if we numerate servers using numbers from 0 to 3, the most functionally
stable variant of connection, based on given budget, may be demonstrated by built graph.</p>
    </sec>
    <sec id="sec-6">
      <title>2.2.2. Second example of usage of described algorithm</title>
      <p>Now let purpose, that it’s needed to connect five servers between each other and we know, that
general budget, what is given for connection, equals 10000$ again, but and prizes for laying every
connection line may be represented by matrix</p>
      <p>Let compare a number of graphs, what was traversed in the process finding of optimal topology.
To do it let use table 1.</p>
      <p>
        As we see on table 1, described method may decrease a number of traversed graphs more, than
30%. It gives excellent optimization in finding of optimal topology of connections of servers. But it
would be interesting to see, for what number of graphs we need do calculate an indicator of
functional stability (
        <xref ref-type="bibr" rid="ref1">1</xref>
        ).
      </p>
      <p>
        As we see on table 2, condition (
        <xref ref-type="bibr" rid="ref2">2</xref>
        ) may guarantee, that for all graphs with allowed number of
connection lines we will estimate indicator of functional stability (
        <xref ref-type="bibr" rid="ref1">1</xref>
        ). In other hand, this factor
combined with (
        <xref ref-type="bibr" rid="ref3">3</xref>
        ) allows to economy a time for comparison in selection of optimal topology. All
this guarantees decreasing of general time, needed for selection of optimal calculations.
      </p>
    </sec>
    <sec id="sec-7">
      <title>3. Conclusions</title>
      <p>This work demonstrates optimized algorithm of finding of topology of network, optimal in sense
of functional stability, considering fixed maximum budget for connection of machines. As examples
and additional analysis shows, described algorithm allows to have excellent optimization in context
of different parameters of difficulty of calculations.</p>
      <p>These results may be used in various fields, for example, in IoT [9, 10], data transmission [11-13]
and processing [14-17], development different systems [18-20], etc.</p>
      <p>Declaration on Generative AI
The author(s) have not employed any Generative AI tools.
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