Blowup of small data solutions for a quasilinear wave equation in two space dimensions

For the quasilinear wave equation partial derivative(t)(2)uu - Delta u = u(t)u(tt), we analyze the long-time behavior of classical solutions with small (not rotationally invariant) data. We give a complete asymptotic expansion of the lifespan and describe the solution close to the blowup point. It turns out that this solution is a "blowup solution of cusp type," according to the terminology of the author [3].