In this section, we aim to provide a comprehensive understanding of the motivation behind the seasons optimization (SO) algorithm. To achieve this, we will explore the underlying numerical model and elucidate its functionality through the use of a basic benchmark function as an illustrative example.
5.1. Natural Phenomena as a Source of Inspiration for the SO Algorithm
Numerous regions across the globe undergo the cyclical occurrence of four distinct seasons, namely spring, summer, autumn, and winter. Each season brings forth exclusive weather patterns that significantly impact the adaptive behaviors of living organisms, particularly trees. By closely observing these natural processes, we derive inspiration for the development of our SO algorithm. Here, we present a concise overview of each season and its relevance to the algorithm:
During the spring season, the advent of warmer temperatures triggers the initiation of new growth cycles. In a manner akin to trees regaining their foliage and generating vital nutrients through the process of photosynthesis, our SO algorithm undergoes a process of “rejuvenation”. It optimizes solutions based on the input data, thereby enhancing its efficacy.
- (B)
Competitive Advantage in Summer
The arrival of summer is accompanied by extended daylight hours and heightened competition among trees for limited resources such as water and soil nutrients. The SO algorithm incorporates similar competitive learning mechanisms, wherein individual agents strive to attain optimal solutions while adapting to the ever-changing environmental conditions.
- (C)
Autumnal Spread and Preparations
During autumn, deciduous trees shed their leaves and disperse seeds, ensuring the propagation of future generations across diverse locations. Analogously, our SO algorithm disperses candidate solutions throughout the search space, thereby expanding the potential for exploration and paving the way for subsequent refinement stages.
- (D)
Winter Survival Strategies
In the face of winter’s harsh conditions, trees enter a state of dormancy to conserve energy until more favorable circumstances return. Similarly, our SO algorithm employs memory structures to store promising solutions that were previously discovered. This enables the algorithm to efficiently utilize computational resources when confronted with challenging optimization problems.
By drawing inspiration from these natural phenomena, the SO algorithm aims to emulate the adaptive and efficient behaviors exhibited by trees in different seasons. Through this approach, we strive to enhance the algorithm’s performance and applicability in solving complex optimization problems.
5.2. Mathematical Representation
This section provides an explanation of how the tree lifecycle is numerically represented across different seasons, which serves as the foundation for the seasons optimizer (SO). This algorithm adopts an iterative approach based on a population, starting with an initial population of trees. All trees within the forest represent a potential solution to a given problem, aiming to identify the most robust tree that corresponds to the optimal solution. The algorithm updates the forest using four primary operators: regeneration, contest, scattering, and survivability. Eventually, the strongest tree is selected as the optimal solution. Refer to
Figure 1 for a visual representation of the flowchart depicting the SO algorithm. The subsequent content presents the mathematical representations of the algorithm’s components.
- -
Initializing the population
Define the problem
as a
-dimensional challenge, depicted as
where
denotes the
ith component of the problem, and
and
represent the lower and upper limits, respectively.
To address the problem
, initially, generate a scattered distribution
, denoted by
where each entity
belonging to
J in the population is expressed as
where
represents the
jth element affiliated with the
ith entity and is achieved as follows:
where
describes a random value in the range [0, 1], and the tree’s strength
has been achieved as follows:
where
represents the assessment criterion linked to the cost factor of the issue, determining the entity’s capacity for reproduction, longevity, and energy retention. Entities with higher influence require more resources, including nutrients, water, and sunlight, which in turn enhance their potential for expansion and propagation.
- -
Renew
Springtime plant behaviors serve as the inspiration for the regeneration operator. In mathematical terms, this can be expressed as
where
represents the population at the
q-th iteration, and
is the set of new sprouts generated through
In this equation,
indicates the number of fallen seeds accumulated until the previous autumn, and
denotes the regeneration proportion, and is achieved as follows:
where
describes the final iteration number, and
determines the current iteration.
and
represent the minimum and the maximum value of
and are considered experimentally 0.4 and 0.6. The function
generates
new sprouts within the habitat. The utilization of
allows for the adjustment of the exploration range, enhancing autonomy in the initial iterations and focusing on local explorations in the later stages.
The regeneration process serves two main purposes: preserving genetic diversity to prevent premature convergence and rejuvenating individuals affected by harsh winter conditions. It is important to note that the regeneration process commences from the second generation (q > 0).
- -
Rivalry
The contention mechanism replicates the effects of the summer season on the growth and progress of plants.
To establish the hierarchy of competition, the trees are organized based on their strength in descending order. Subsequently,
of the most resilient trees are selected to generate the core tree list
. For each tree
in
, the following inequality holds:
The value of
is determined as follows:
The stochastic variable, denoted as
, identifies the subset of trees designated as cored trees. The remaining set of trees, denoted as
, consists of neighboring trees, each of which is closely associated with a cored tree. The number of neighbors for a cored tree
is determined by
where
stands for the normalized strong point of
, and is achieved by the following equation:
In the subsequent step, a set of
trees is randomly selected from the neighboring trees to form the neighborhood region of the central tree
. Within each neighborhood region
, the impact of competition on a tree
is indicated by the following equation:
The variable
represents the condition of tree
during repetition
.
denotes the level of competition or density index, which measures the influence of neighboring trees on tree
. The function
evaluates the growth of tree
under similar circumstances when its neighbors are not present. The function
is defined by the following equation:
Such that,
stands for a random vector, and
represents the basis of the number, distance, and strong point of neighbors:
The strong point of the kth neighbor, denoted as
, and the distance between the kth neighbor and the tree
, denoted as
, are important factors in determining the influence of a neighbor
on the tree
, represented by the constant
. The distance
is calculated according to the following equation:
The value of
is determined based on the number of variables in the tree, denoted by
.
The stochastic asymmetry factor, , lies between 0 and 1 and represents the degree of asymmetry in rivalry. It varies from zero, indicating fully symmetric rivalry, to one, indicating fully asymmetric rivalry.
This factor determines the extent to which the influence of a relatively minor neighboring tree is discounted. If a minor neighbor tree has fewer strong points, it will have less impact on the tree
. However, if the fittest neighbor is identified, it will replace
. The algorithm employs a “winner takes all” approach to calculate the novel situation of the cored tree,
. Among
’s neighbors, the tree with the highest number of strong points is selected and replaced with
.
In a cored tree represents the highest neighboring tree. The strength of the trees is influenced by the rivalry between them. Typically, it is probable that the strong trees will become even stronger while the weak trees will become weaker. However, in the SO algorithm, during the rivalry phase, both strong and weak trees have the opportunity to improve and become stronger.
Therefore, after the rivalry, if it is determined that the strength of a particular tree has been significantly diminished compared to its previous state, then the former highest position of the tree will be considered for future reference.
- -
Seeding
The machinist simulates how trees scatter their seeds during autumn. To scientifically simulate the seeding process, a random selection of trees is made to create the seeding list
. These trees will then disperse their seeds in the forest. The total number of seeds (
) is determined by the following equation:
Here,
defines a random value for the rate of seeding,
selects the strongest
trees from the jungle. To prevent the jungle from growing too large, each tree only produces one seed every fall. Therefore, the number of seeds in each generation of the algorithm is
. From each nominated tree
, a random number of variables are chosen, and their values are replaced with newly generated random values of the same type. Let
be the variables chosen from the tree
, where
is a random number less than
. The new value of each variable
can be achieved by the following equation:
where
is a random value between
and
, and
represents a 2-valued variable (±1).
- -
Persistence
The operative who never gives up studies how winter affects the trees. They remove the weakest trees from the jungle. The trees that are not very strong are considered weak. The impact of persistence on the jungle can be shown by the formula:
where
represents the weak trees cluster that will be removed from the jungle. This is calculated by the formula:
where
removes
trees from the jungle. The persistence ratio
is determined by the formula:
where
describes a negative value representing the critical temperature at which trees may be damaged and fall.
ranges between −100 and 0, but for consistency, it is drawn between −1 and 0.
All trees may or may not survive the persistence stage based on their strength. During the renewal stage, seeds that fell in the previous fall sprout and become new trees in the jungle, leading to an increase in the jungle’s size after multiple cycles. To maintain the jungle’s size and prevent it from growing, is set to where is the seeding ratio. Therefore, after completing a full cycle of the algorithm, the number of trees in the jungle will be the same as the initial number.
5.4. Algorithm Authentication
This section seeks to confirm the efficiency of the proposed advanced seasons optimizer in identifying the best solution for optimization issues. To accomplish this, we carried out experiments on two unimodal and two multimodal basic problems. Our goal was to assess the capability of the ASO in delivering optimal solutions for these problems.
To evaluate the performance of the ASO algorithm in comparison to other metaheuristic algorithms, we employed five additional metaheuristics from the existing literature, Grey Wolf Optimizer (GWO) [
8], Whale Optimization Algorithm (WOA) [
9], Pelican Optimization Algorithm (POA) [
2], Multi-verse optimizer (MVO) [
10], and Tunicate Swarm Algorithm (TSA) [
11]. All test functions utilized in this study were formulated for minimization purposes. The alternative parameters of the optimizers are outlined in
Table 2.
Set parameters of the ASO algorithm were determined through experimental analysis, specifically tailored for the selected problem. It is important to note that these parameters may vary when applied to different problems. To validate the effectiveness of the suggested EGSA technique, we conducted tests using the “CEC-BC-2017 test suite”, which is a widely recognized benchmark system. The evaluation was performed on 10 random benchmark functions, including F1, F3, F5, F7, F9, F11, F13, F15, F17, and F19, with decision variables in the range [−100, 100]. To guarantee a consistent assessment against alternative methods, a standard configuration was established for all compared algorithms.
Table 3 displays a comparison examination of the proposed ASO in conjunction with other metaheuristic techniques tested on the CEC-BC-2017 benchmark suite. Presented here is a demonstration of the ASO’s exceptional competence in addressing complex global optimization challenges.
As can be observed from
Table 3, it is evident that the ASO algorithm has demonstrated significant success by achieving the lowest average error in eight out of fifteen cases (F1, F3, F5, F7, F9, F11, F13, and F15) and tying with the GWO in one case (F2). Additionally, the ASO consistently shows reduced variation, indicating a high level of reliability. These results provide strong evidence supporting the superior performance of the ASO algorithm in handling complex optimization tasks when compared to other alternatives. However, there are still areas for improvement, which should encourage researchers to explore new strategies for addressing challenging optimization problems. In summary, the insights gained from
Table 3 underscore the importance of continuous advancements in metaheuristic optimization algorithms.