@article{CIOBAN_2018, title={AROUND THE POINCARE CENTER-FOCUS PROBLEM}, volume={6}, url={https://revista.ust.md/index.php/acta_exacte/article/view/364}, DOI={10.36120/2587-3644.v6i2.11-19}, abstractNote={<p><span class="fontstyle0">It is well known that many mathematical models use differential equation systems and apply the qualitative theory of differential equations, introduced by Poincar´e and Liapunoff. One of the problems that persists in order to control the behavior of systems of this type, is to distinguish between a focus or a center (the Center-Focus Problem). The solving of this problem goes through the computation of the Poincar´e Liapunoff quantities. The problem of estimating the maximal number of algebraically independent essential constants is called the Generalized Center-Focus Problem. The present article contains: some moments related to the history of the Center-Focus Problem; the contribution of the Academician C. Sibirschi’s<br>school in the solving of the Center-Focus Problem; methodological aspects of the M. N. Popa and V. V.<br>Pricop solution of the Generalized Center-Focus Problem.</span></p>}, number={2}, journal={Acta et Commentationes Exact and Natural Sciences}, author={CIOBAN, Mitrofan}, year={2018}, month={Dec.}, pages={11-19} }