2 papers
math.CA2004
On the configuration of limit cycles in planar vector fields
Ali Taghavi
We prove that coexistence of two limit cycles with disjoint interior can not occur in certain quadratic systems
math.DS2004
An Index Interpretation For the Number Of Limit Cycles Of A Vector Field
Ali Taghavi
We show that the number of limit cycles of Lienard vector field L is equal to the index of first order linear PDE defined by L.