  In this paper, we consider the blow-up problem of semilinear generalized
Tricomi equation. Two blow-up results with lifespan upper bound are obtained
under subcritical and critical Strauss type exponent. In the subcritical case,
the proof is based on the test function method and the iteration argument. In
the critical case, an iteration procedure with the slicing method is employed.
This approach has been successfully applied to the critical case of semilinear
wave equation with perturbed Laplacian or the damped wave equation of
scattering damping case. The present work gives its application to the
generalized Tricomi equation.
