“…The relatively small improvement between (1) and (2) in terms of degrees proves useful while searching for a Hopf Bifurcation. Indeed, the Routh-Hurwitz criterion applied on systems (1) and (2) leads to semi-algebraic systems of the form h 1 , h 2 , h 3 , h 4 = 0, h 5 , h 6 , h 7 > 0, with respective degrees 9, 2, 9, 42, 12, 20, 23 in the case of (1), and smaller degrees 7,2,7,32,8,14,19 in the case of (2).…”