*4.3. Constrained Optimization*

#### 4.3.1. Linear and Nonlinear Constrained Optimization

Strumberger et al. [164] presented a hybridized elephant herding optimization (HEHO) algorithm to solve constrained optimization problems. Thirteen standard constrained benchmark functions were conducted for evaluating the efficiency and robustness of the HEHO algorithm. The simulation results were compared with other state-of-the-art algorithms, such as firefly algorithms, seeker optimization algorithms, and self-adaptive penalty function genetic algorithms. The study results showed that the proposed HEHO was more e fficient than the other reported algorithms.

#### 4.3.2. Economic Dispatch Problems
