  Boson-Sampling holds the potential to experimentally falsify the Extended
Church Turing thesis. The computational hardness of Boson-Sampling, however,
complicates the certification that an experimental device yields correct
results in the regime in which it outmatches classical computers. To certify a
boson-sampler, one needs to verify quantum predictions and rule out models that
yield these predictions without true many-boson interference. We show that a
semiclassical model for many-boson propagation reproduces coarse-grained
observables that were proposed as witnesses of Boson-Sampling. A test based on
Fourier matrices is demonstrated to falsify physically plausible alternatives
to coherent many-boson propagation.
