  We discuss the reaction of associated production of a top quark pair and a
Higgs boson at the future e+e- linear collider that can be used to determine
the top-Higgs Yukawa coupling. Taking into account decays of the top quarks and
the light Higgs boson leads to reactions with 8 fermions in the final state
which, in the framework of the standard model, receive contributions typically
from many thousands Feynman diagrams. An overwhelming majority of the diagrams
comprises the off resonance background to the resonant signal of associated
production and decay of the top quark pair and Higgs boson. We address the
signal and background issue by comparing cross sections calculated with the
signal diagrams only and with the complete sets of the diagrams.
