[en] We present data on composite particle production as a function of multiplicity for different colliding systems and energies (Ca+Ca at 400 and 1050 MeV/n and Nb+Nb at 400 and 650 MeV/n). These data can be understood by the improved coalescence model taking the radius and temperature of the participant region, as well as the radius of the deuteron into account. The obtained radii for the interacting volume give chemical freeze out densities between 50 and 100% of normal nuclear density. We also present results on entropy production in the system studied by considering two different models for the determination of the entropy. The results show large differences which clearly show that the determination of entropy produced in nuclear collisions is strongly model dependent. Favoring the model by Stoecker we conclude that compression is achieved in the collision and that the normal no-compression fireball model produces too much entropy. Thus the glogally measured d/p ratios together with a proper method for the entropy determination allows one in principle to distinguish between different equations of state. A determination of the proper equation of state from data, however, would be improved by a model which does not need to extrapolate from the finite size volumes in nuclear collisions to that of infinite matter, but rather uses the higher accuracy of the experimental data themselves. The findings that compression is needed to explain the entropy values can be related to the pressure effect observed in form of collective flow (side-splash). The flow phenomenon can now be connected with nuclear compression and not thermal pressure alone. 19 references