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Harmony search (HS) is a metaheuristic algorithm (also known as soft computing algorithm or evolutionary algorithm) mimicking the improvisation process of musicians. A metaheuristic is a Heuristic method for solving a very general class of computational problems by combining user-given black-box procedures €”usually heuristics Soft computing refers to a collection of computational techniques in Computer science, Machine learning and some engineering disciplines which study model and analyze In Artificial intelligence, an evolutionary algorithm (EA is a Subset of Evolutionary computation, a generic population-based Metaheuristic In the process, each musician plays a note for finding a best harmony all together. Likewise, each decision variable in optimization process has a value for finding a best vector all together.

Contents

The algorithm

Harmony search tries to find a vector x that minimizes some cost function.

The algorithm as given by [2] is:

  1. Initialize the harmony memory: pick k random vectors x^1 \ldots x^k.
  2. Make a new vector x'. For each component x'i:
    • with probability phmcr pick the component from memory, x'_i = x^{rand()}_i
    • with probability 1 − phmcr pick a new random value in the allowed range.
  3. Pitch adjustment: For each component x'i:
    • with probability ppar change x'i by a small amount, x'_i \leftarrow x'_i \pm bw\cdot rand().
    • with probability 1 − ppar do nothing.
  4. If x' is better than the worst xi in the memory, then replace xi by x'.
  5. Repeat from step 2 until a maximum number of iterations has been performed.

The parameters of the search are

It is possible to vary the parameters as the search progresses, this gives an effect similar to simulated annealing. Simulated annealing (SA is a generic probabilistic Meta-algorithm for the Global optimization problem namely locating a good approximation to the

In improved harmony search, ppar is increased linearly, while bw is decreased exponentially.

Harmony search applications

The HS algorithm had been successful in a wide variety of optimization problems in the following fields.

Bench-mark problems

Real-world problems

Harmony search features

HS has several advantages when compared with traditional gradient-based mathematical optimization techniques as follows:

Also, the HS algorithm could overcome the drawback of genetic algorithm's building block theory by considering the relationship among decision variables using its ensemble operation. A genetic algorithm (GA is a Search technique used in Computing to find exact or Approximate solutions to optimization and Search

Other Related Algorithms

References

General Information

Theory of Harmony Search

Applications in Artificial Intelligence

Applications in Engineering


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