On Random Search for a Global Extremum

1984 ◽  
Vol 28 (1) ◽  
pp. 136-141 ◽  
Author(s):  
S. M. Ermakov ◽  
A. A. Zhiglyavskii
1989 ◽  
Vol 29 (1) ◽  
pp. 112-117 ◽  
Author(s):  
S.M. Ermakov ◽  
A.A. Zhigyavskii ◽  
M.V. Kondratovich

Author(s):  
Yevgeniy Bodyanskiy ◽  
Alina Shafronenko ◽  
Iryna Pliss

The problem of fuzzy clustering of large datasets that are sent for processing in both batch and online modes, based on a credibilistic approach, is considered. To find the global extremum of the credibilistic fuzzy clustering goal function, the modification of the swarm algorithm of crazy cats swarms was introduced, that combined the advantages of evolutionary algorithms and a global random search. It is shown that different search modes are generated by a unified mathematical procedure, some cases of which are known algorithms for both local and global optimizations. The proposed approach is easy to implement and is characterized by the high speed and reliability in problems of multi-extreme fuzzy clustering.


2019 ◽  
Vol 85 (1(I)) ◽  
pp. 72-77 ◽  
Author(s):  
S. M. Ermakov ◽  
D. N. Semenchikov

A new known modification for simulation of annealing to search the global extremum of the functions of many variables uses the fact that the function whenn→ ¥ converges to the δ-function concentrated at the point of global maximum off(x). The case when the function has many equal extrema is discussed in detail. Problems of this type are often present, particularly in the design of regression experiments. Here we introduce the reader to an extremum search method that is effective in solving a wide range of applied problems, and also illustrate the use of the method in some of the simplest problems of designing the regression experiments. The proposed modification of simulated annealing uses quasi-random search at the intermediate stages. This is not the most rapid, but very reliable method which provide a complete exploring of the function domain. When solving numerical examples, the so-called exactD-optimal designs are constructed, which are very difficult to be obtained by other methods. Although with the increase in the number of variables, the complexity of the method (as well as the complexity of other well-known methods) increases dramatically due to an increase in the order of the determinant, the proposed algorithm is simple, reliable, and easily parallelized. It is known that the gain from using optimal designs in some cases can justify any computational costs of developing those designs. Using the described technique, the reader will be able to construct (even using the laptop capacity) the optimal designs in different areas at moderate values of the parameters (for example, for quadratic regression for s variables in variables fors≤ 10).


2020 ◽  
Vol 46 (8) ◽  
pp. 609-618
Author(s):  
N. Vershkov ◽  
M. Babenko ◽  
V. Kuchukov ◽  
N. Kuchukova

Algorithms ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 139 ◽  
Author(s):  
Vincenzo Cutello ◽  
Georgia Fargetta ◽  
Mario Pavone ◽  
Rocco A. Scollo

Community detection is one of the most challenging and interesting problems in many research areas. Being able to detect highly linked communities in a network can lead to many benefits, such as understanding relationships between entities or interactions between biological genes, for instance. Two different immunological algorithms have been designed for this problem, called Opt-IA and Hybrid-IA, respectively. The main difference between the two algorithms is the search strategy and related immunological operators developed: the first carries out a random search together with purely stochastic operators; the last one is instead based on a deterministic Local Search that tries to refine and improve the current solutions discovered. The robustness of Opt-IA and Hybrid-IA has been assessed on several real social networks. These same networks have also been considered for comparing both algorithms with other seven different metaheuristics and the well-known greedy optimization Louvain algorithm. The experimental analysis conducted proves that Opt-IA and Hybrid-IA are reliable optimization methods for community detection, outperforming all compared algorithms.


2018 ◽  
Vol 27 (4) ◽  
pp. 643-666 ◽  
Author(s):  
J. LENGLER ◽  
A. STEGER

One of the easiest randomized greedy optimization algorithms is the following evolutionary algorithm which aims at maximizing a function f: {0,1}n → ℝ. The algorithm starts with a random search point ξ ∈ {0,1}n, and in each round it flips each bit of ξ with probability c/n independently at random, where c > 0 is a fixed constant. The thus created offspring ξ' replaces ξ if and only if f(ξ') ≥ f(ξ). The analysis of the runtime of this simple algorithm for monotone and for linear functions turned out to be highly non-trivial. In this paper we review known results and provide new and self-contained proofs of partly stronger results.


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