=Paper= {{Paper |id=Vol-2711/paper47 |storemode=property |title=Model and Algorithms for Synthesis of Bi-Assignment |pdfUrl=https://ceur-ws.org/Vol-2711/paper47.pdf |volume=Vol-2711 |authors=Yuriy Fedosenko,Dmitriy Khandurin,Anatoliy Sheyanov |dblpUrl=https://dblp.org/rec/conf/icst2/FedosenkoKS20 }} ==Model and Algorithms for Synthesis of Bi-Assignment== https://ceur-ws.org/Vol-2711/paper47.pdf
    Model and Algorithms for Synthesis of Bi-Assignment

         Yuriy Fedosenko[0000-0002-9434-4386], Dmitriy Khandurin[0000-0003-2485-525X],
                         Anatoliy Sheyanov[0000-0003-3550-4068]
    1Volga State University of Water Transport, Nesterova str., 5, Nizhny Novgorod, 603950,

                                              Russia
          fds1707@mail.ru, 2kaf_isut@vsuwt.ru, 3asheyanov@ya.ru



       Abstract. In discrete idealization, a mathematical model of the assignment of the
       pairs of non-interchangeable tasks between the agents is formulated. The model
       describes, in particular, the state of the water transport logistics system at the de-
       cision-making moment during planning the usage of a group of heterogeneous
       cargo ships. Within the framework of the formulated model, the concept of “bi-
       assignment” is introduced and optimization problem of bi-assignment with a
       minimax criterion is posed, which generalizes the classical assignment problem.
       For the task and its practically significant refinements, the intractability is
       proved. Solving algorithms implementing the concept of dynamic programming
       and the branch-and-bound scheme are constructed. Examples of the numerical
       implementation of the bi-assignment synthesis are given. The developed model
       and algorithm are implemented in the logistics management support system in
       the Kazan river port.

       Keywords: assignment problem, bi-assignment, dynamic programming, branch-
       and-bound scheme, computational complexity


1      Introduction

The classical assignment problem (AP) (linear balanced assignment problem) – a prob-
lem of optimal, in one sense or another, assignment of the finite n-element collection of
tasks between the same number of agents was first formulated in 1952 by
Votaw, D. F., Jr. and Orden, A. in [1].
   Subsequently, the AP served as the basis for setting various modifications and ap-
plied interpretations, including flexible production systems, determining the location of
production facilities and so on.
   A detailed analysis of the models and varieties of the assignment problem is pre-
sented, for example, in the overview chapters of [2, 3].
   The development and research of algorithms for solving AP also have a long history
since the early work of Kuhn H.W. [4] describing the method for solving the AP
named by the author "Hungarian method".
   This method and the method of potentials, as well as their modifications developed
in recent years, are the main regular methods for synthesizing exact solutions of the AP
[5, 6].

Copyright © 2020 for this paper by its authors. Use permitted under Creative Commons
License Attribution 4.0 International (CC BY 4.0). ICST-2020
    By these methods, the AP is solved in polynomial time of the size of the input.
Among the numerous approaches developed for the synthesis of approximate solutions
of the AP we note the algorithms developed on the basis of the heuristic concepts [7,
8].
    Nowadays, due to the intensive development and integration in everyday practice of
digital support management applications, in particular, in the operational planning of
logistics and production and transportation processes [9], there is a need for advanced
models for the distribution of discrete resources.
    One of these extensions relates to the pair distribution of non-interchangeable re-
sources (tasks) between the agents considered in the article.
    As an example, we will point to the production and transport system [10], in which a
selected group of non-identical river cargo ships is used for transporting sand and
gravel mixture (SGM) to specified storage (consumption) points, loaded in a single
technological cycle by floating hydro-mechanized mining complexes (HMC) on large-
scale area of riverbed deposits. In such a system, up to 10 – 15 HMC units can be in-
volved, and the same number of ships arrives daily for loading.
    At the end of the development session of the next operational plan for the function-
ing of the system under consideration, it should be unambiguously determined:

• to which HMC unit from the number of riverbed deposits located at the area, each
  specific ship should be sent for loading SGM;
• which unloading destination should be assigned to each specific ship after loading
  the SGM.

   For the automated formation of operational plans for the operating of the production
and transportation system, effective in the conditions of a current operating environ-
ment, the computer control support complex should include both a digital modeling
system module and tools for solving the corresponding optimization problem of ship
allocation between the HMC for loading SGM and ships distribution at SGM unload-
ing points.
   As a second example, we will mention the problem of paired distribution of high-
speed passenger ship destinations along routes for mass transportation in megacities,
regional and island agglomerations.
   The purpose of this article is to develop a mathematical model for the distribution of
pairs of non-interchangeable tasks between the agents, formulate an optimization prob-
lem with a minimax criterion, construct decision-making algorithms acceptable for
practical use, and consider the computational complexity of the problem and its special
cases.
   It is in this way that the material of the article is presented, which includes six sec-
tions, two appendixes and References.
   In the next (second) section a mathematical model for the pair use of discrete re-
sources of the type in question is formulated, and the general problem of bi-assignment
with a minimax criterion is stated, generalizing AP with a minimax criterion (Linear
bottleneck assignment problem).
   This problem is denoted in the article as GBAP (generalized bi-assignment prob-
lem).
    The third section of the article is devoted to the construction of a discrete dynamic
programming algorithm [11, 12], which allows one to synthesize exact solutions of the
GBAP posed in the second section; an estimate of its computational complexity is
given here [13] and, as an illustration, the result of the implementation of the algorithm
on the numerical data of the example is given.
    In the fourth section, an algorithm for the synthesis of optimal and suboptimal bi-
assignments in the process of iterative synthesis of the solution of GBAP according to
the branch-and-bound scheme is constructed.
    The fifth section is devoted to two practically significant special cases of the GBAP,
including taking into account the laboriousness of tasks and the productivity of agents;
it is established that all these problems are intractable [9], algorithms of polynomial
computational complexity cannot be built for them.
    The sixth section of the article is Conclusion
    Appendix 1 and 2 contains step-by-step implementations of the constructed dynamic
programming algorithms and branches and boundaries for the example of GBAP given
in the third section.


2      Formal Problem Statement

Let there be a set of agents I = {1, 2, … , n} and two sets of tasks P = {p1, p2, … , pn}
and Q = {q1, q2, … , qn}. Each agent must be assigned to one of the tasks of the set P
and one of the tasks of the set Q. Each of the tasks must be completed in full by only
one agent.
   The (nn)-matrices A = {aij} and B = {bij} of numerical estimates are assumed to be
given, where aij is the cost of execution of the task pj by the agent i, bij is the cost of the
execution of the task qj by the same agent, i = 1, n , j = 1, n .
    Let us introduce the following notation: π1 = {π1(i), i = 1, n } is the set of assign-
ments of agents to tasks from the set P, π2 = {π2(i), i = 1, n } is the set of assignments
of agents to tasks from the set Q.
    Both the assignment π1 and the assignment π2 are a bijection of the set
I = {1, 2, … , n} to itself (permutation).
    The equality π1(i) = j means the appointment of agent i to task pj. Similarly, the
equality π2(i) = j means the appointment of agent i to task qj.
    We denote pairs of the form < π1(i), π2(i) > as bi-assignment; it is supposed that
when implementing bi-assignment < π1(i), π2(i) >, each agent i, first starting from time
0 performs task with the number π1(i), and then immediately proceeds to task with the
number π2(i), i = 1, n .
    In a general form, a GBAP with a minimax criterion is written as follows:

                             min (max[a1 ( ) + b2 ( ) ])                            (1)
                             1 ,  2   
    If matrices A and B set the processing time of the task by the agents, then solving
(1), we look for a bi-assignment that ensures the minimality of the total processing
time of the entire complex of tasks {p1, p2, … , pn, q1, q2, … , qn}.
    It is easy to see that (1) is a generalization of AP.


3      Construction of a Solving Algorithm Based on the Dynamic
       Programming Concept

Let i be a natural constant not exceeding n, W1, W2 be arbitrary i-element subsets of
{1, 2, … , n}.
    By Z(i, W1, W2) we denote the subproblem of the problem (1), in which among the
agents of the set I one should distribute tasks with lower indices (numbers) from the
subsets W1 and W2; in this case, each agent should receive only one task from the set Р
with a subscript included in the subset W1, and only one task from the set Q with the
index included in the subset W2. The optimal value of the criterion of the problem (1) is
denoted by Bopt.
    According to the concept of dynamic programming [12], the state of the process of
the pair distribution of the tasks of the sets P, Q between the agents of the set I at step i
is uniquely determined by the triple (i, W1, W2), where i is a natural constant not ex-
ceeding n, restricting the assignment to agents with numbers 1, 2, ..., i, and W1, W2
arbitrary i -element subsets of the sets of indices of the tasks P, Q, respectively, availa-
ble for distribution.
    The optimal criterion value in the problem Z(i, W1, W2) is denoted by B(i, W1, W2).
B(i, W1, W2) is the Bellman function for problem (1), and

                         B(1, {j}, {k}) = a1j + b1k; j, k N.                           (2)

    According to the optimality principle, for solving problem (1), we write the follow-
ing recurrent relations of dynamic programming

          B(i, W1, W2) = min (max[(ai + bi ), B(i -1, {W1\  }, W2\  })]),           (3)
                                 ,


            Bopt(n, I, I) = min (max[(an + bn ), B(n-1, (I \  }, I \  ))]),         (4)
                                  ,


where (α, β) are arbitrary pairs of indices from the set W1W2.
    The implementation of the computational algorithm along these relations, denoted
below by DP, begins with the determination of the quantities B(1, {j}, {k}) for all sin-
gleton sets W1 и W2.
    Next, sequentially in increasing order of parameter i for all possible sets W1 and W2,
the values of the Bellman function B(i, W1, W2), i = 1, n − 1 are determined by formula
(3).
    The value B(n, I, I) determined by relation (4) is the optimal criterion value Bopt in
problem (1).
     In the process of executing the DP algorithm for each triple (i, W1, W2) of the val-
ues of the arguments of the Bellman function, we should fix the pair (α, β) on which
the minimum of the right-hand side of relations (3), (4) is realized. This will allow,
after finding the optimal value of the Bopt criterion, to uniquely determine the corre-
sponding bi-assignment.
     Relations (2) - (4) suppose implementation of the direct calculation scheme, with-
out taking into account the state, unattainable from the initial one.
     We specify below a phased implementation of the described synthesis algorithm for
solving problem (1).
     Stage 1. The initial triple (1, {j}, {k}) and empty lists G and G* are initialized. By
the formula (2), the values of the Bellman function B(1, {j}, {k}) are calculated at
j, k = 1, 2, … , n. Goes to stage 2.
     Stage 2. For values of i satisfying the inequality i < n, we calculate the values of the
Bellman function B(i, W1, W2) by the formula (3) for all possible subsets of the indices
W1 and W2 of tasks from respectively the sets P and Q of dimension i; list G is updated
with entries of the form (i, W1, W2, α*, β*), where α*, β* are the values of the indices α,
β, at which the optimal value of the function B(i, W1, W2), i = 2, 3, … , n-1 is reached.
Otherwise, i.e. if i = n, go to stage 3.
     Stage 3. By the formula (4), the value of the Bellman function Bopt(n, I, I) is calcu-
lated. The entry (n, I, I, α*, β*) is added to the list G; the loop counter z is set to n, the
working arrays V1, V2 are initialized according to the relations V1 = I, V2 = I. Go to
stage 4.
     Stage 4. An element corresponding to the triple (z, V1, V2) is selected from the list
G. The entry (z, α*, β*) is added to the list G*; for z = n, n -1, … , 2, the operations
z = z-1, V1 = V1 \ α*, V2 = V2\ β* are performed.
     Stage 5. Ending the DP algorithm: the list G* contains the optimal solution to prob-
lem (1).
     The complexity of the DP algorithm is determined by the number of calculated val-
ues of the Bellman function and is determined by the value О(4n).
     As an illustration, we present the result of executing the DP algorithm on the nu-
merical data of problem (1) with square matrices of the form

                        70 35 10 68      69 73 32 15 
                                                     
                        72 68 69 12      85 3 39 96 
                     A=              ; B=                                              (5)
                         42 62 8 96        1 3 6 31 28 
                                                     
                        50 60 98 84      3 33 54 51 
                                                     

    The optimal value of the criterion Bopt(n, I, I) = 53 in the above example problem
(5) is achieved with bi-assignment of the form

                      πp(1) = 2, πp(2) = 4, πp(3) = 3, πp(4) = 1,                        (6)

                      πq(1) = 4, πq(2) = 2, πq(3) = 3, πq(4) = 1.

   Step-by-step execution of the DP algorithm is reproduced in tables 2 – 5 of Appen-
dix 1.
4       Construction of a Solving Algorithm Based on the Branch-
        and-Bound Paradigm

The implementation of the branch-and-bound paradigm [14] consists in constructing a
fragment of the variant tree sufficient to determine the optimal solution. The vertices of
this tree correspond to states (i, 1 , 2 ), where i is the number of assigned agents,
 1 , 2 are the subsets of the sets P and Q that determine the assignments of agents
{1, 2, ... , i}; in particular, the root of the variant tree corresponds to the triple
(0, {ø}, {ø}).
    The algorithm, hereinafter referred to as WG, for the implementation of the compu-
tational procedure according to the branch-and-bound scheme is completely deter-
mined by defining the methods for:
    a) obtaining upper bounds UB for the values of minimax criterion (1) at the con-
structed vertices of the variant tree (in minimization problems, the upper bound is pro-
vided by a feasible solution);
    b) obtaining lower bounds for LB at the constructed vertices of the variant tree;
    c) branching regulating the order of traversal of vertices.
    To obtain an upper bound of the minimax criterion (1) in the root of the variant tree,
the following four possible options for paired assignments should be considered:

1. 1* (i) = i, *2 (i) = i;
2. 1* (i) = i, *2 (i) = n – i + 1;
3. 1* (i) = n – i + 1, *2 (i) = i;
4. 1* (i) = n – i + 1, *2 (i) = n – i + 1

and select a paired assignment with a minimum value of max ([a1 (  ) + b2 ( ) ]) .
                                                                

    The bi-assignment < 1* (i), *2     (i) > 
                                               **
                                                    thus formed provides an upper bound for
UB in the root of the variant tree.
   It is easy to see that, as a lower bound of LB at the root, we can take the quantity de-
termined by the formula
                                  max[min a + min b ] .
                                                  


    The above methods for obtaining bounds of UB and LB at the root induce procedures
for finding the upper and lower bounds in the vertices obtained at all subsequent inter-
mediate vertices of the variant tree.
    The smallest of the UB bounds obtained during the calculation is called the record
Rec; initially, the record values are assumed to be +∞, while the in WG algorithm exe-
cution process, the record value decreases.
    The branching procedure consists in assigning the next agent to tasks from the sets
P and Q, respectively, and pruning out the subsets of feasible solutions that knowingly
do not contain optimal solutions.
    When branching for agent i, all tasks pj and qk are considered, for which previous
agents of the current branch were not assigned. Thus, we obtain (n − i + 1)(n − i + 1)
new vertices.
    Branching at the vertices in which the LB bound exceeds the existing record value is
not performed as impractical.
    As an example, on the numerical data of problem (1) with square matrices (5), the
execution of the WG algorithm up to obtaining the optimal bi-assignment (6) is repro-
duced step-by-step in tables 6–10 in Appendix 2. For a clear presentation of the solu-
tion process in these tables the operator K(i, 1 , 2 ) transforming the current
(i, 1 , 2 ) state is introduced.
    The result of applying this operator is a pair of numerical values corresponding to
the lower bound LB and the upper bound UB of the minimax criterion values (1) in the
constructed vertex of the variant tree.
    The root of the decision tree corresponds to the state (0, {ø}, {ø}); the result of ap-
plying the operator to this state according to the procedures described above is the pair
{53, 107}, the current record Rec becomes 107.
    To evaluate the performance of the software implementation of the WG algorithm
in comparison with the performance of the software implementation of the DP algo-
rithm, computational experiments were performed on a test data set.
    For each dimension n = 10 – 13, a hundred problems were solved, determined by
the square matrices of numerical estimates A and B of the corresponding dimension.
    The integer values of the elements of the matrices aij, bij were generated in a pseu-
do-random manner according to the uniform distribution law on the interval [0, 99].
    The duration of the test run of each algorithm was measured to the nearest second.
The experimental results are shown in table 1.

                            Table 1. Results of the experiments

    The value of                  The average execution time of the algorithm
  dimension n of
  the problem (1)                   DP                                 WG
         10                          37                                   8

         11                         174                                  30

         12                         912                                 476
         13                        4377                                4314


    In production and transport applications, in the presence of strict regulatory re-
strictions on the duration of solving problem (1), it is advisable to synthesize approxi-
mate solutions.
    In this context, the principal advantage of the WG algorithm is the ability to termi-
nate it as soon as the set time limit for the task has been exhausted. In this case, an
estimate of the deviation of the obtained approximate value of the minimax criterion
from its optimal value will be known.
5      Special Cases of the General Problem of Bi-Assignment,
       Estimates of Computational Complexity

As a concretization, we introduce GBAPhw in which each of the available 2n tasks is
characterized by the labor consumption of h, so task pj has labor consumption of h(pj),
task qj – h(qj); each agent i is characterized by performance wi. With that, the elements
of the matrices of numerical estimates А and В are calculated by the formulas

                  aij = h(pj) / wi , bij = h(qj) / wi, i = 1, n , j = 1, n .

    Under these conditions, for GBAP and GBAPhw problems, the following recogni-
tion problems corresponding to them can be distinguished.
    Problem 1: with the initial GBAP data and the additional constant T, it is asked if
there is a bi-assignment, implementation of which executes the entire set of available
tasks no later than the time instant T.
    Problem 2: with the initial data GBAPhw and additionally indicated constant T, the
restriction is established by analogy with problem 1.
    The computational complexity of GBAP is no less than the computational complex-
ity of GBAPhw, Problem 1 and Problem 2; the computational complexity of GBAPhw
and Problem 1 is no less than the computational complexity of Problem 2.
    It is easily shown that Problem 2 in polynomial time can be reduced to the problem
“matching with weight restrictions,” which, in turn, is NP-complete [13].
    Thus, the intractability of both the general problem of bi-assignment and the partic-
ular modifications considered in this section is established; according to the accepted
hypothesis about the distinction of the classes of problems P and NP, it is not possible
to construct decisive algorithms of polynomial computational complexity for these
problems.


6      Conclusion

The article proposes a mathematical model of the assignment between the agents of
pairs of non-interchangeable tasks. The model describes, in particular, the state of the
production and transport system at the decision-making moment when planning the
usage of a group of heterogeneous cargo ships.
    In the framework of the formulated model, the concept of “bi-assignment” is intro-
duced and bi-assignment problem with a minimax criterion, which generalizes the
classical assignment problem, is posed. The intractability of the task and its practically
meaningful special cases is proved.
    Solving algorithms, implementing concepts of dynamic programming and branches
and bounds, are constructed.
    As an example, the result of a phased implementation of bi-assignment synthesis
for a problem with square matrices numerical estimates of fourth-order is given.
   For practically significant for industrial transport applications values of dimension
n = 10 – 13, the results of massive computational experiments on a comparative evalu-
ation of the performance of developed algorithms are presented.
   The results obtained demonstrate the importance of the developed algorithms for
use, for example, in digital systems of support planning of the distribution of high-
speed passenger ships along routes for mass transportation in megacities, regional and
island agglomerations.
   Prospects for further research are to modify the proposed model for a wider range of
applied problems, including those requiring multi-criteria formulation [15].
   In terms of mathematical models and the general problem of bi-assignment, charac-
terized by increased dimensions and, accordingly, requiring practically unacceptable
calculation time for their implementation, it is advisable to focus on the development
of algorithms based on metaheuristic concepts [16], as well as oriented to supercom-
puter technologies for the implementation of computational processes [17, 18].
   Acknowledgments. This paper has been prepared as a result of studies financially
supported by the Russian Foundation for Basic Research, project no 15-07-03141.


Appendix 1
                                    Table 2. Values of B(1, {j}, {k})

       j\k                     1                         2                3                     4
           1                  139                     143               102                  85
           2                  104                     108                 67                 50
           3                  79                      83                  42                 23
           4                  137                     141               100                  83

               Table 3. Values of B(2, W1, W2) for subsets W1, W2 of dimension 2

  W1 \ W2        {1, 2}             {1, 3}           {1, 4}    {2, 3}          {2, 4}           {3, 4}
  {1, 2}           104               111              153        75             75                  107
  {1, 3}            79               111              154        75             75                  108
  {1, 4}           137               102                 97     100             83                   85
  {2, 3}            79               107              153         71            71                  107
  {2, 4}           104                97                 97       67            50                   51
  {3, 4}            79                79                 97       42            25                   52

               Table 4. Values of B(3, W1, W2) for subsets W1, W2 of dimension 3

   W1 \ W2          {1, 2, 3}                {1, 2, 4}        {1, 3, 4}                 {2, 3, 4}
   {1, 2, 3}             71                     71              197                        71
   {1, 2, 4}             67                     50               51                        70
   {1, 3, 4}             43                     43               51                        70
   {2, 3, 4}             63                     50               51                        50
                    Table 5. Values of B(4, W1, W2) for subsets W1, W2 of dimension 4

   W1 \ W2             {1, 2, 3, 4}
 {1, 2, 3, 4}          53

   Cyclically performing selections of items from the list G and adding to the list G *
according to Stage 4 of the DP algorithm, we’ll obtain the solution to problem (1) in
the form of bi-assignment (6) corresponding to Bopt(n, I, I) = 53.


Appendix 2

                    Table 6. The results of operator K(i, 1 , 2 ) on the current state 1.

                                                                           K(i, 1 , 2 )
 (i, 1 ,  2 )
                                                               LB                        UB
 1, {1}, {1}                                                  139                        139
 1, {1}, {2}                                                  143                        143
 1, {1}, {3}                                                  102                        111
 2, {1, 2}, {3, 1}                                            153                        153
 2, {1, 2}, {3, 2}                                            102                        102
 Rec = 102

                    Table 7. The results of operator K(i, 1 , 2 ) on the current state 2.

                                                                K(i, 1 , 2 )
 (i, 1 , 2 )
                                                    LB                                   UB
 2, {1, 2}, {3, 4}                                 164                                  164
 2, {1, 3}, {3, 1}                                 154                                  154
 2, {1, 3}, {3, 2}                                 102                                  102
 2, {1, 3}, {3, 4}                                 165                                  165
 2, {1, 4}, {3, 1}                                 102                                  111
 2, {1, 4}, {3, 2}                                 102                                  102
 2, {1, 4}, {3, 4}                                 108                                  108
 1, {1}, {4}                                         85                                 107
 2, {1, 2}, {4, 1}                                 153                                  153
 2, {1, 2}, {4, 2}                                   87                                   87
 Rec = 87
                  Table 8. The results of operator K(i, 1 , 2 ) on the current state 3.

                                                                         K(i, 1 , 2 )
                   (i, 1 , 2 )
                                                               LB                             UB
2, {1, 2}, {4, 3}                                             107                             107
2, {1, 3}, {4, 1}                                             154                             154
2, {1, 3}, {4, 2}                                              85                              93
3, {1, 3, 2}, {4, 2, 1}                                       138                             138
3, {1, 3, 2}, {4, 2, 3}                                        93                              93
3, {1, 3, 4}, {4, 2, 1}                                       114                             114
3, {1, 3, 4}, {4, 2, 3}                                       127                             127
2, {1, 3}, {4, 3}                                             108                             108
2, {1, 4}, {4, 1}                                              97                             114
2, {1, 4}, {4, 2}                                              85                             101
3, {1, 4, 2}, {4, 2, 1}                                       152                             152
3, {1, 4, 2}, {4, 2, 3}                                        97                             114
2, {1, 4}, {4, 2}                                              85                             101
3, {1, 4, 2}, {4, 2, 1}                                       152                             152
3, {1, 4, 2}, {4, 2, 3}                                       101                             101
3, {1, 4, 3}, {4, 2, 1}                                       114                             114
3, {1, 4, 3}, {4, 2, 3}                                        85                              85
Rec = 85

                  Table 9. The results of operator K(i, 1 , 2 ) on the current state 4.

                                                                           K(i, 1 , 2 )
(i, 1 , 2 )
                                                                    LB                        UB
2, {1, 4}, {4, 3}                                                   85                        93
1, {2}, {1}                                                      104                          104
1, {2}, {2}                                                      108                          108
1, {2}, {3}                                                         67                        101
2, {2, 1}, {3, 1}                                                157                          157
2, {2, 1}, {3, 2}                                                   87                         87
2, {2, 1}, {3, 4}                                                168                          168
2, {2, 3}, {3, 1}                                                154                          154
2, {2, 3}, {3, 2}                                                   72                         87
3, {2, 3, 1}, {3, 2, 1}                                          135                          135
3, {2, 3, 1}, {3, 2, 4}                                             87                         87
3, {2, 3, 4}, {3, 2, 1}                                       101                       101
3, {2, 3, 4}, {3, 2, 4}                                       124                       124
2, {2, 3}, {3, 4}                                             165                       165
2, {2, 4}, {3, 1}                                              97                       101
2, {2, 4}, {3, 2}                                              67                       101
3, {2, 4, 1}, {3, 2, 1}                                       149                       149
3, {2, 4, 1}, {3, 2, 4}                                       101                       101
3, {2, 4, 3}, {3, 2, 1}                                       101                       101
3, {2, 4, 3}, {3, 2, 4}                                        67                          67
Rec = 67

              Table 10. The results of operator K(i, 1 , 2 ) on the current state 5.

                                                           K(i, 1 , 2 )
(i, 1 , 2 )
                                                LB                                UB
2, {2, 4}, {3, 4}                              108                                108
1, {2}, {4}                                     53                                104
2, {2, 1}, {4, 1}                              157                                157
2, {2, 1}, {4, 2}                               87                                 87
2, {2, 1}, {4, 3}                              111                                111
2, {2, 3}, {4, 1}                              154                                154
2, {2, 3}, {4, 2}                                72                                87
2, {2, 3}, {4, 3}                              108                                108
2, {2, 4}, {4, 1}                               97                                104
2, {2, 4}, {4, 2}                               53                                101
3, {2, 4, 1}, {4, 2, 1}                        152                                152
2, {2, 3}, {4, 3}                              108                                108
2, {2, 4}, {4, 1}                               97                                104
2, {2, 4}, {4, 2}                               53                                101
3, {2, 4, 1}, {4, 2, 1}                        152                                152
3, {2, 4, 1}, {4, 2, 3}                        101                                101
3, {2, 4, 3}, {4, 2, 1}                        104                                104
3, {2, 4, 3}, {4, 2, 3}                         53                                 53
Rec = 53
 Thus, the optimal value of criterion (1) equal to 53 is achieved on bi-assignment (6).
References

 1. Votaw, D. F., Jr., Orden, A.: The personnel assignment problem. In Symposium on
    Linear Inequalities and Programming. Scientific Computation of Optimum Pro-
    grams. Project SCOOP, Washington, D.C., no. 10, pp. 155-163 (1952).
 2. Medvedeva, O. A.: Modeli i algoritmy resheniya mnogokriterial'nyh zadach o
    naznacheniyah s dopolnitel'nymi ogranicheniyami.
    https://www.dissercat.com/content/modeli-i-algoritmy-resheniya-
    mnogokriterialnykh-zadach-o-naznacheniyakh-s-dopolnitelnymi-ogr/read (date of
    request 01.08.2020).
 3. Medvedev, S. N.: Obobshchyonnye modeli zadachi o naznacheniyah i adaptivnye
    algoritmy ih resheniya. https://www.dissercat.com/content/obobshchennye-modeli-
    zadachi-o-naznacheniyakh-i-adaptivnye-algoritmy-ikh-resheniya (date of request
    01.08.2020).
 4. Kuhn, H. W.: The Hungarian Method for the assignment problem. Naval Research
    Logistics Quarterly, vol. 2, pp. 83-97 (1955).
 5. Morales, D. R., Romeijn, H. E.: The Generalized Assignment Problem and Exten-
    sions. Handbook of Combinatorial Optimization. Supplement vol. В. Springer,
    pp. 259-312 (2005).
 6. Pentico, D.: Assignment problems: A golden anniversary survey. European Journal
    of       Operational        Research,       no. 176,     pp. 774-793       (2007).
    doi:10.1016/j.ejor.2005.09.014
 7. Gonzalez T.F. (ed.): Handbook of Approximation Algorithms and Metaheuristics:
    Methologies and Traditional Applications, vol. 1. N.Y. Chapman and Hall/CRC
    (2018). doi:https://doi.org/10.1201/9781351236423
 8. Medvedev, S. N., Medvedeva, O. A.: An adaptive algorithm for solving the axial
    three-index assignment problem. Automation and Remote Control, vol. 80, pp.
    718-732 (2019). doi: 10.1134/S000511791904009X
 9. Kogan, D. I., Fedosenko, Yu. S., Handurin, D. A.: Problem definition and solving
    algorithms for assignment problem applied to task of vehicle trains assembling.
    Bulletin of the Volga State Academy of Water Transport, no. 52. VSUWT publish-
    ing house, N. Novgorod, pp. 23-30 (2017).
10. Kogan, D. I., Trukhina, M. A., Fedosenko, Yu. S., Sheyanov, A. V.: Models and
    optimization problems for single-processor servicing of packets of objects. Auto-
    mation and Remote Control, vol. 77, no 11, pp. 994-2005 (2016).
    doi:10.1134/S0005117916110096
11. Aris, R.: Discrete dynamic programming: an introduction to the optimization of
    staged processes. Blaisdell Pub. Co., Waltham, MA (1964).
12. Dreyfus, S. E., Bellman, R. E.: Applied Dynamic Programming. Princeton Univ.
    Press, Princeton, N.J. (1971).
13. Garey, M. R., Johnson, D. S.: Computers and Intractability: A Guide to the Theory
    of NP-Completeness. W. H. Freeman and Co., New York (2003).
14. Land, H., Doig, A. G.: An automatic method of solving discrete programming
    problems. Econometrica, vol. 28, no 3, pp. 497-520 (1960) doi: 10.2307/1910129
15. Kogan, D. I., Fedosenko, Yu. S.: Handurin, D. A.: Concepts and algorithms for
    solving multi-criteria modifications of the assignment problem. Bulletin of the
    Volga State Academy of Water Transport, no. 53. VSUWT publishing house,
    N. Novgorod, pp. 25-31 (2017).
16. Blum, C., Roli, A.: Metaheuristics in combinatorial optimization: Overview and
    conceptual comparison. ACM Computing Surveys, no 35(3), pp. 268-308 (2003).
    https://doi.org/10.1145/937503.937505
17. Cuencaa, J., Gimnezb, D., Martnez, J.: Heuristics for work distribution of a homo-
    geneous parallel dynamic programming scheme on heterogeneous systems. Parallel
    Comput. 31(7), pp. 711-735 (2005).
     doi:https://doi.org/10.1016/j.parco.2005.04.005
18. Fedosenko Yu., Reznikov M.: A Model of FPGA Massively Parallel Calculations
    for Hard Problem of Scheduling in Transportation Systems. In: Battiti, R. et al.
    (Eds): Learning and Intelligent Optimization. LION 2017, LNCS, vol. 10556,
    pp. 370-375 (2017). doi:https://doi.org/10.1007/978-3-319-69404-7_33