A.G. Ivakhnenko's 1971 paper, “Polynomial Theory of Complex Systems,” published in IEEE Transactions on Systems, presents a novel approach to modeling complex systems using polynomial functions. Ivakhnenko details the development and application of the Group Method of Data Handling (GMDH), a method that constructs models of varying complexity through iterative processes. The paper highlights how polynomial functions can be used to capture the intricate relationships within complex systems and how the GMDH algorithm can automatically determine the optimal model structure, including the number of layers, which could reach up to eight. This approach allows for the creation of highly accurate predictive models and has had a profound impact on the advancement of machine learning and systems theory. Ivakhnenko's work laid the groundwork for future developments in deep learning and adaptive systems, providing essential techniques for the analysis and modeling of complex data.