Artificial Immune Recognition System #

Name #

Artificial Immune Recognition System (AIRS)

Taxonomy #

AIRS is a biologically inspired optimization algorithm based on the principles of the human immune system. It is closely related to other immune-inspired algorithms such as Clonal Selection Algorithm and Negative Selection Algorithm.

• Computational Intelligence
  • Biologically Inspired Computation
    • Artificial Immune Systems
      • Clonal Selection Algorithm
      • Negative Selection Algorithm
      • Artificial Immune Recognition System (AIRS)

Strategy #

AIRS mimics the behavior of the human immune system, specifically the processes of antibody production and antigen recognition. The algorithm maintains a population of artificial immune cells, each representing a potential solution to the optimization problem.

Affinity Maturation #

During the affinity maturation phase, the algorithm selects the immune cells with the highest affinity (fitness) to the antigen (problem) and undergoes a process of cloning and mutation. This process allows the immune cells to explore the solution space and potentially discover better solutions.

Memory Cell Selection #

After the affinity maturation phase, the algorithm selects the best performing immune cells to become memory cells. These memory cells represent the best solutions found so far and are used to guide the search process in subsequent iterations.

Diversity Maintenance #

To maintain diversity in the population and prevent premature convergence, AIRS employs a mechanism called resource competition. This process ensures that immune cells that are too similar to each other are eliminated, promoting a diverse set of solutions.

Procedure #

1. Initialize:
   1. Create an initial population of artificial immune cells
   2. Evaluate the affinity (fitness) of each immune cell
2. Repeat until termination criteria are met:
   1. Affinity Maturation:
      1. Select the best performing immune cells
      2. Clone and mutate the selected cells
      3. Evaluate the affinity of the cloned and mutated cells
   2. Memory Cell Selection:
      1. Select the best performing immune cells from the affinity maturation phase
      2. Add the selected cells to the memory cell pool
   3. Diversity Maintenance:
      1. Perform resource competition among the immune cells
      2. Remove immune cells that are too similar to each other
3. Return the best solution found (memory cell with the highest affinity)

Data Structures #

• Population: A collection of artificial immune cells representing potential solutions
• Memory Cell Pool: A subset of the population containing the best performing immune cells
• Affinity: A measure of the fitness or quality of an immune cell (solution)

Parameters #

• Population Size: The number of artificial immune cells in the population
• Clonal Rate: The number of clones generated for each selected immune cell during affinity maturation
• Mutation Rate: The probability of mutation for each cloned immune cell
• Affinity Threshold: The minimum affinity required for an immune cell to be selected for cloning and mutation
• Diversity Threshold: The minimum distance required between immune cells to maintain diversity

Considerations #

Advantages #

• Inherent diversity maintenance through resource competition
• Ability to balance exploration and exploitation through affinity maturation and memory cell selection
• Adaptability to dynamic environments due to the continuous learning nature of the algorithm

Disadvantages #

• Computational complexity can be high, especially for large population sizes and high-dimensional problems
• Sensitive to parameter settings, requiring careful tuning for optimal performance
• May struggle with highly constrained optimization problems due to the stochastic nature of the search process

Heuristics #

Population Size #

• Start with a moderate population size (e.g., 50-100) and adjust based on problem complexity
• Larger populations can improve exploration but increase computational cost
• Smaller populations may converge faster but risk getting stuck in local optima

Clonal Rate #

• Higher clonal rates encourage exploitation of promising solutions
• Lower clonal rates promote exploration of the solution space
• Adjust the clonal rate based on the desired balance between exploration and exploitation

Mutation Rate #

• Higher mutation rates introduce more diversity but can slow down convergence
• Lower mutation rates focus the search around existing solutions but may limit exploration
• Adapt the mutation rate based on the stage of the search process (e.g., higher rates early on, lower rates later)

Affinity Threshold #

• Set the affinity threshold based on the desired quality of solutions
• Higher thresholds are more selective but may discard potentially useful solutions
• Lower thresholds are more inclusive but can slow down convergence

Diversity Threshold #

• Set the diversity threshold based on the desired level of population diversity
• Higher thresholds maintain more diversity but may slow down convergence
• Lower thresholds allow more similar solutions but risk premature convergence

Termination Criteria #

• Define clear termination criteria based on the problem requirements (e.g., maximum number of iterations, target solution quality)
• Consider using a combination of criteria to balance computational cost and solution quality
• Implement early stopping mechanisms to avoid wasting resources on unproductive search

Problem Representation #

• Choose a suitable representation for the problem at hand (e.g., binary, real-valued, permutation)
• Consider the nature of the problem constraints and objective function when selecting a representation
• Ensure that the representation allows for meaningful mutation and affinity evaluation operations

Affinity Evaluation #

• Define an appropriate affinity function that accurately measures the quality of solutions
• Consider the computational cost of the affinity function, especially for large-scale problems
• Normalize the affinity values to ensure fair comparison between solutions

Parameter Adaptation #

• Implement adaptive mechanisms to automatically adjust algorithm parameters during the search process
• Use feedback from the search progress to guide parameter adaptation (e.g., increase mutation rate if progress stagnates)
• Experiment with different adaptation strategies and select the one that works best for the problem at hand