Our aim is to study ordinary di?erential equations or simply di?erential s- tems in two real variables x ? = P(x, y), (0.1) y? = Q(x, y), r 2 where P and Q are C functions de?ned on an open subset U of R, with ? r=1,2, ..., ?, ?.AsusualC standsforanalyticity.Weputspecialemphasis onto polynomial di?erential systems, i.e., on systems (0.1) where P and Q are polynomials. Instead of talking about the di?erential system (0.1), we frequently talk about its associated vector ?eld ? ? X = P(x, y) +Q(x, y) (0.2) ?x ?y 2 on U? R . This will enable a coordinate-free approach, which is typical in...
Our aim is to study ordinary di?erential equations or simply di?erential s- tems in two real variables x ? = P(x, y), (0.1) y? = Q(x, y), r 2 where P ...
