Displaying similar documents to “On the critical periods of Liénard systems with cubic restoring forces.”

A polynomial with 2k critical values at infinity

Janusz Gwoździewicz, Maciej Sękalski (2004)

Annales Polonici Mathematici

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We construct a polynomial f:ℂ² → ℂ of degree 4k+2 with no critical points in ℂ² and with 2k critical values at infinity.

The Łojasiewicz gradient inequality in a neighbourhood of the fibre

Janusz Gwoździewicz, Stanisław Spodzieja (2005)

Annales Polonici Mathematici

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Some estimates of the Łojasiewicz gradient exponent at infinity near any fibre of a polynomial in two variables are given. An important point in the proofs is a new Charzyński-Kozłowski-Smale estimate of critical values of a polynomial in one variable.

Quadratic vector fields with a weak focus of third order.

Joan C. Artés, Jaume Llibre (1997)

Publicacions Matemàtiques

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We study phase portraits of quadratic vector fields with a weak focus of third order at the origin. We show numerically the existence of at least 20 different global phase portraits for such vector fields coming from exactly 16 different local phase portraits available for these vector fields. Among these 20 phase portraits, 17 have no limit cycles and three have at least one limit cycle.