TWO PROBLEMS OF PLANAR QUADRATIC SYSTEMS

【摘要】 <正> The main results of this paper are as follows: （ⅰ） The important formulas, given by Bautin, of three focal quantities for the specific form of quadratle system （E₂） have been generalized to the general form of （E₂）. （ⅱ） By using the method in [13], a kind of （E₂） possessing at least four limit cycles is given. Theorem 2 herein contains the results in [11--13] on （1,3）-distribution of limit cycles of （E₂）.更多还原

【Abstract】 The main results of this paper are as follows: （ⅰ） The important formulas, given by Bautin, of three focal quantities for the specific form of quadratle system （E₂） have been generalized to the general form of （E₂）. （ⅱ） By using the method in [13], a kind of （E₂） possessing at least four limit cycles is given. Theorem 2 herein contains the results in [11--13] on （1,3）-distribution of limit cycles of （E₂）.更多还原