“…Regarding the semilinear Euler-Poisson-Darboux equation and, more in general, the semilinear wave equation with scale-invariant damping and mass (i.e. (1) for ℓ = 0), combining the contributions from many different authors (see [4,7,25,19,29,30,8,22,5,3] and references therein) we may reasonably conjecture that for nonnegative µ, ν 2 such that the quantity…”