In bifurcation theory, a field within mathematics, a Bogdanov-Takens bifurcation is a well-studied example of a bifurcation with co-dimension two, meaning that two parameters must be varied for the bifurcation to occur. It is named after Rifkat Bogdanov and Floris Takens, who independently and simultaneously described this bifurcation.
A system y' = f(y) undergoes a Bogdanov-Takens bifurcation if it has a fixed point and the linearization of f around that point has a double eigenvalue at zero (assuming that some technical nondegeneracy conditions are satisfied).
Three codimension-one bifurcations occur nearby: a saddle-node bifurcation, an Andronov-Hopf bifurcation and a homoclinic bifurcation. All associated bifurcation curves meet at the Bogdanov-Takens bifurcation.
The normal form of the Bogdanov-Takens bifurcation is
It has also been found the existence of a codimension-three degenerate Takens-Bogdanov bifurcation, also known as Dumortier-Roussarie-Sotomayor bifurcation.