1. Introduction
The decision-making process involves some difficulties such as choosing among a large number of criteria, and alternatives, the determination of the importance of the criteria (i.e., the weights of the criteria), collecting the related information about the problem, and developing a model for the decision-making problem [
1,
2,
3]. The process also requires significant time and effort to analyze the numerous actions using systematic techniques. In particular, decision-making under uncertainty is more difficult since there is no knowledge about the player’s behavior [
4]. These types of games are known as the games against nature in the literature. Games against nature are the games in which the payoffs in the game are unknown and the probability with which the player will choose his/her actions is entirely unknown [
5,
6]. Pazek and Rozman stated how a player decides under uncertainty in [
7] as follows:
Make a list of all possible alternatives for obtaining knowledge, experimenting, and taking action.
List all events that may possibly occur.
Arrange all relevant data and choices/assumptions.
Sort the effects of each choice of action on a scale.
Determine the probability of an uncertain event occurring.
Over time, some mathematical methods have been developed for decision-making under uncertainty. For example, Laplace, Wald, Hurwicz, and Savage presented some criteria for these types of games [
8,
9,
10]. On other hand, the results of decisions not only depend on the decisions themselves, but also on some exterior factors that cannot be controlled by the player. The word “nature” in games against nature stands for the entirety of these external factors. The state of nature refers to the complete explanation of the external factors concerning all aspects of the situation [
11]. Researchers have improved the methodologies and presented more complex algorithms to find an answer for such decision processes, which are known as decision criteria under uncertainty or multicriteria decision methods. Then, these methods are applied to various types of problems. For example, the criteria under uncertainty are usually applied to agricultural problems in the literature due to the unpredictable behavior of nature [
7,
12,
13]. However, the application area of these criteria is not limited to only agricultural applications. For example, in 2006, Ballestero et al. used these criteria to analyze the best portfolio options in the Frankfurt and Vienna Stock Exchanges [
14]. In 2007, Ünal and Atılgan applied the decision-making techniques to the apparel industry [
15]. Galasso and Thiery, in 2009, investigated the consumer–supplier relationship using these criteria [
16].
Green and Weatherhead, in 2014, studied the climate change problem with the criteria under uncertainty [
17]. In 2019, Ma et al. used the multicriteria decision technique to select a portfolio fulfilling the requirement [
18]. In 2020, İzgi and Özkaya considered the necessity of the agricultural insurance problem by these criteria with a method called the matrix norm approach from game theory [
12]. In the same year, Yazdani et al. used the multicriteria methods to decide the optimal location of healthcare waste disposal [
19]. Furthermore, in 2020, Saldanha et al. showed that multicriteria decision-making under uncertainty provides a rational solution to shell-and-tube heat problems [
20]. In 2021, Ulansky and Raza proposed an approach that generalized the decision criteria under uncertainty [
21]. Shmelova et al. investigated the selection of the optimal location for a remote tower center by using the criteria of Laplace, Wald, Savage, and Hurwicz [
22]. Pak et al., in 2021, applied the criteria for assessing the economic efficiency of investment projects under the conditions of radical and probabilistic uncertainties [
23]. Shmelova and Sechko studied the hybrid expert system for collaborative decision-making in transportation services of healthcare needs by using the decision criteria under uncertainty [
24]. Wang et al. aimed to develop an indicator framework for integrated monitoring of the costing process for a patient by rehabilitation medical institutions with the help of decision criteria [
25]. Balasa et al., in 2022, investigated the risk management and risk control in a wind tunnel by the criteria under uncertainty [
26]. Gomes and Martins represented the details of the decision criteria under uncertainty in their book in detail and also presented some applications of the criteria [
27]. Balakina et al. used the criterion under uncertainty to demonstrate how large-scale railway projects of federal significance should be computed [
28]. Vdovyn et al. used Hurwicz, Bayes–Laplace, Wald, Savage, and another decision criterion to model economic systems by game theory [
29]. Walker et al. studied the effects of future developments on buildings’ greenhouse gas emissions by scenario-based robustness assessment with the help of decision criteria [
30].
In addition to these, in this paper, we mainly focus on the methods established by Laplace, Wald, Hurwicz, and Savage and combine the 3D matrices together. All the definitions and applications above are modeled with two-dimensional matrices and related matrix operations. However, it may be more useful to model a problem with higher-dimensional matrices depending on the type of problem since those matrices may express and reflect the problem better than it is stated in two dimensions. To develop a higher-dimensional model with matrices, scientists began by defining the 3D matrices in the literature. Even though there are many different definitions of the 3D matrices, we ground ourselves on the definitions in [
31]. İzgi, in 2015, explicitly defined and proved 3D matrix norms with details in his Ph.D. thesis. Additionally, the applications of the 3D matrix norms to mathematical finance were presented in [
31,
32]. In 2017, İzgi and Özkaya stated and proved the equivalence of the 3D matrix norms. They demonstrated an application of these norms’ inequalities on some simulation results obtained by real data using the methods of mathematical finance [
33]. In 2018, İzgi and Özkaya presented the fundamental definitions and properties of three-dimensional matrices [
34].
Besides the numerous theoretical studies about 3D matrices in the literature, there are different applications of 3D matrices in physics, electrical engineering, mathematical finance, etc. In 1979, Cosima proved that, if each of the horizontal plane sections of the
, three-dimensional matrix
A, has full-term rank, then the plane term rank of the 3D matrix
A is larger than
, where
, which is used in physics [
35]. In 1996, Burkard et al. investigated 3D assignment problems as considering the cost coefficients can be decomposed into three different values [
36]. In 2006, Ignatova and Styczynski showed the graphical representation of the transition number matrix and the Markov matrix in 3D [
37]. As seen from the studies above, three-dimensional matrices have a wide range of use in the literature.
In this paper, we specifically study the decision under uncertainty and its fundamental criteria such as those of Laplace, Wald, Hurwicz, and Savage. These criteria consist of only one state; in other words, these criteria may refer to the single-state decision criteria. We present the extension of the criteria under uncertainty to the three-dimensional cases by adding a second state of nature in the payoff matrix by considering that the decision-making process in real-life problems is usually affected by more than one factor. Therefore, we extend the definitions of the Laplace, Wald, Hurwicz, and Savage criteria to the three-dimensional case to capture and analyze the effects of the second state of nature, the multiple state decision criteria. In the literature, there are studies about the multiple criteria/multicriteria decision-making process [
38,
39,
40]. However, this study improves the multiple-state decision-making process based on the decision criteria under uncertainty and 3D matrices. The number of states may be increased by the usage of higher-dimensional matrices. According to our literature review, the decision and game theories come together with the 3D matrices for the first time in this study. Thus, we aim to bring a new perspective to game theory and decision theory by these extensions, that is the multi-state decision criteria, via the usage of 3D matrices.
The remainder of the paper is organized as follows: In
Section 1.1, we present some theoretical background and definitions of Laplace, Wald, Hurwicz, and Savage. In
Section 2, we present the characteristic axioms of the criteria in 3D. Moreover, we define the three-dimensional decision criteria such as those of Laplace, Wald, Hurwicz, and Savage. Additionally, we demonstrate that each criterion satisfies the characteristic axioms of the criteria in 3D. In
Section 3, we give a fundamental example explaining the usage of the 3D criteria. Furthermore, we present real-life problems modeled with 3D matrices and solve them by using the 3D decision criteria, explicitly.
Section 4 concludes the paper.
1.1. Some Theoretical Background
In this section, we present some notions and definitions that are used as a basis throughout the study. To show the correspondence between the state of nature and actions selected by a player, we first focus on the representation of the game against nature. The consequences of actions depending on states are usually represented as in
Table 1, including the outcome of the actions [
6,
11].
In decision theory, there are different types of decisions such as decision under risk, decision under certainty, decision under uncertainty, and multicriteria decision [
5,
41]. The types of uncertainty are called by different authors in various [
42,
43,
44]. However, we can summarize them as follows [
11]:
Definition 1 (First type of uncertainty). The player knows the states of nature.
Definition 2 (Second type of uncertainty). The player knows that states of nature, but not the probabilities.
Definition 3 (Third type of uncertainty). The player knows both the states of nature and the probabilities.
The player decides the decision rule after stating the problems clearly and analyzing the situations. The best-known decision-making rules are those of the Laplace, Wald, Hurwicz, and Savage criteria, among others [
11].
Definition 4 (Laplace criterion).
Let denote the probabilities of the n states of nature and denote the outcomes by the usage of the action chosen by the player within the state of nature. The Laplace value, also known as the expected monetary value, for the action is evaluated as Then, the Laplace criterion implies the action with a maximum so that we select In addition to this definition, Laplace defines the criterion in [8] as a maximum of Definition 5 (Wald criterion).
The worst potential outcome that might occur as a result of action has a value for the decision-maker of where is the security level of the action . Wald recommends that the player should select the action with the highest security level as: Definition 6 (Hurwicz criterion).
Hurwicz established an optimistic criterion by taking into account the best-possible result of each action. The optimism level is defined as where is the best result if action is taken. Hurwicz’s maximax return criterion is Hurwicz also defined the optimism–pessimism index
z with
in 1951 by considering a balance between maximum optimism and pessimism [
9]. Moreover, Hurwicz proposed the decision rule with regard to the index
z as:
In the same year, 1951, Savage proposed a criterion containing the comparison of the result of every action with the results of other actions under the same state of nature [
10].
Definition 7 (Savage criterion).
Let the regret refers to the difference between the values coming from the best action given that is the true state of nature and the value resulting from under : By the regret matrix of values, every action should be assigned the index of worst regret resulting from action : Savage’s minimax regret criterion is defined as: 3. Examples: Multiple State Games
In this section, we present some useful illustrations of the criteria in three dimensions. The first example aims to show the usage of the criteria in detail. The second and third examples demonstrate the real-life applications of these criteria. The third dimension treats the time and speed of the wind in the second and third examples, respectively.
Example 1 (Fundamental example).
The main purpose of this example is to show the application of the criteria in three dimensions comprehensively, as was done in [5,45] for two-dimensional matrices. Let A be a 3D matrix in , and define it as follows: Figure 1 represents the 3D form of matrix
A above. Each section in
Figure 1 refers to the sections
,
, and
from front to back, respectively. In other words, the entries of the most front section of
Figure 1 are
for
and
j = 1, 2, 3, 4.
Laplace criterion: We used the simplest form of the definition of the Laplace criterion in 3D as we may choose the row-block providing the highest average of the sum of the elements in the row-blocks. Therefore, we evaluated them by using
for
, so that
and similarly
and
,
are calculated. Then,
by the definition. Hence, the Laplace would suggest that the player choose the first row-block (i.e., Alternative 1).
On the other hand, we can easily evaluate the result of the Laplace criterion in 3D by using the 3D matrix norm definition presented in Definition 11 as
Similar to the original definition of the Laplace criterion in 3D, the norm definition also suggests Alternative 1. The advantage of using the 3D norm definition of the Laplace criterion is that the result is obtained quickly without any intermediate calculation steps.
Wald criterion: We use the definition of the Wald criterion and follow the steps of the definition in three dimensions as
Thus, the Wald criterion in 3D recommends preferring Alternative 2. In other words, the Wald criterion says that the best decision is the second row-block.
Hurwicz criterion: As we did in the analysis of the Wald criterion above, we follow the definition of the Hurwicz criterion in three dimensions and obtain the following:
In order to compare the results for different optimism index
, which is the indecision point for this example between the 2nd and 3rd row-blocks, we first consider the case while
; as an example, we chose
, then we have
According to the Hurwicz criterion, the best alternative is Alternative 3 (i.e., the third row-block) while
. We now examine the case when
. As an illustration, let
.
Hence, the Hurwicz criterion advises preferring Alternative 2 (i.e., the second row-block) for .
Savage criterion: We firstly obtain the positive regret matrix
R by using
in Definition 14 as
Then, we use the rest of the definition as
and
Hence, the best decision is Alternative 4 according to the Savage criterion in 3D. In other words, Savage recommends the fourth row-block to the player.
We can summarize the obtained results via three-dimensional representation in
Figure 2, which shows the composite form of the 3D matrix
A. For example, the Laplace criterion suggests choosing Alternative 1. In other words, the yellow row-block refers to the result of the Laplace criterion in 3D. Similarly, the green, blue, and purple row-blocks refer to the results of the Wald, Hurwicz (for
), and Savage criteria, respectively.
Example 2 (COVID-19 stages with real data).
Let be 3D matrix, which is created by using real data for South Korea [46], and denotes the stages of the COVID-19 pandemic as the start, spread, and end for and 3
, respectively. In this modeling, the actions are keeping the quarantine and breaking the quarantine while the state of nature is the different infection risk of the individuals in the stages. Accordingly, we have the following 3D matrix A: Laplace criterion: We used the alternative definition of the Laplace criterion for the 3D matrix as follows:
Similarly, we evaluated
as above. Then,
. Therefore, the Laplace criterion suggests the first row-block, that is keeping the quarantine is the best alternative.
On the other hand, we can easily evaluate the Laplace criterion by Definition 11. However, we need to perturb the matrix by adding a 3D matrix with all entries of 0.987 in order to obtain a non-negative matrix in light of Remark 1. By the norm definition of the Laplace criterion applied on the perturbed 3D matrix, we have
that points out to the first row-block.
Wald criterion: In order to determine which row-block suggested by the Wald criterion, we applied Definition 12 step by step and obtain the following:
Consequently, it is clear by the value that the Wald criterion implies Alternative 1/the first row-block is the best option.
Hurwicz criterion: Similarly, we used Definition 13 by choosing the optimism index
as an example, then
while
Hence, the Hurwicz criterion advises selecting Alternative 1. In other words, according to the Hurwicz criterion, the best option for the player is the first row-block.
Savage criterion: Firstly, we created the regret matrix using
and obtain
Next, we followed the rest of the definition of the Savage criterion in three dimensions as
Thus, Savage suggests the best alternative as Alternative 1 (i.e., the first row-block).
It is well known in the literature that the combination of wind and hailstorms increases the risk of a lower harvest of fruits [
47,
48]. In light of this fact, we reconsidered the problem given in [
12] and extended it to the three-dimensional case to examine the simultaneous effects of the hailstorm and wind speed on the harvest of apricot fruit in the following example under the perspective of decision criteria for the necessity of agricultural insurance.
Example 3 (Agricultural insurance with hailstorms and the speed of the wind).
In this example, we used the data for the hailstorm given in [47] and for the effect of the wind in [48]. We considered that the loss of the farmer would be doubled when the wind speed doubled during the hailstorm since the hailstorm and the wind speed affect the production of apricot fruit in the field. We assumed that the maximum loss of the farmer would be −20,000 since the total value of the harvest is 20,000 in [47]. Then, the 3D payoff matrix is generated as follows:Firstcolumn-block and second column-block: “Hail storm does not exist” and “Hail storm exists”
First row-block and second row-block: “Insurance unavailable” and “Insurance available” Here, Aks, for , represent the case for different wind speeds with the hailstorm situations. More explicitly, , , and refer to the situations with the wind speeds of 0, 20, and 40 kph, respectively, and the hailstorm cases.
Laplace criterion: We applied the definition of the Laplace criterion in 3D and evaluated and . Then, . Therefore, the Laplace criterion suggests the best alternative to be the second row-block.
We can also recalculate the criterion result with Definition 11 by using the fact in Remark 1, which means we added the matrix A with a 3D matrix with all entries of 20000, as , which says the best option is the insurance available action.
Wald criterion: By the Wald criterion stated in Definition 12, we have
The best action is the second row-block according to the Wald criterion result.
Hurwicz criterion: We directly applied the steps of the Hurwicz criterion given in Definition 13 with the optimism index, for instance,
, and we obtain
Furthermore, we have the following via the recommended Hurwicz criterion decision rule in 3D:
Thus, the Hurwicz criterion encourages preferring the action of insurance available.
Savage criterion: By the Savage criterion in 3D, we first obtain the regret matrix
R as
Then, we obtain from the rest of the steps the following:
The best alternative is the second row-block with respect to the Savage criterion.
4. Conclusions and Discussions
The main goal of these extensions is to discover the simultaneous effects of two states of nature on the decision process in 3D. For this purpose, we extended the Laplace, Wald, Hurwicz, and Savage criteria to three dimensions under uncertainty. In addition to these definitions, we presented a new definition for the Laplace criterion, based on only the ∞-norm of the 3D payoff matrix, which reduces the computational costs and obtains results quickly.
Then, we presented all 3D characteristic axioms for the Laplace, Wald, Hurwicz, and Savage criteria to demonstrate the effects of the third dimension theoretically. After giving the proofs of the propositions for all criteria, we stated that the criteria in three dimensions work well for any two-dimensional matrix if the third dimension is assumed as 1. Finally, we presented an illustrative fundamental example in order to show the application of the 3D decision criteria explicitly. Moreover, we showed the applicability of the 3D decision criteria on real-life problems, as well. We used the real data belonging to South Korea during the different stages of the first wave of the COVID-19 pandemic. Although it is hard to handle different stages’ effects simultaneously in 3D matrix analyses, the 3D criteria helped us obtain the results easily, and they both suggested the best alternative during the COVID-19 pandemic to be the keeping the quarantine strategy while different factors were affecting the individuals’ decision process.
Additionally, we investigated an agricultural insurance problem in 3D, which is based on natural events’ (wind and hailstorm) effects, as another important real-life action. Under a similar complexity of the decision process in 3D, we simply concluded that it is necessary to obtain agricultural insurance for the apricot field in any weather condition with the guidance of the 3D criteria.
Consequently, we believe that the extensions of the criteria in 3D may have a wide application area. The usage of the criteria in three dimensions might especially be useful for some problems that contain two simultaneous states of nature. We also think that the applications of 3D matrices in decision and game theories may make it easier or take an important role to model some complex situations. For example, in the case of more than two states of nature, these cases cannot be modeled directly by the three-dimensional matrix. Therefore, these cases need higher-dimensional matrices, which require comprehensive work depending on the theoretical studies for the higher-dimensional matrices. Thus, the extensions and contributions of this paper could be the base for higher-dimensional extension research. On the other hand, since we focused on three-dimensional extensions of the criteria in this paper, this may be considered as a limitation of the study in view of theoretical and practical implications. The higher-dimensional extensions of the criteria are left for future research.