form during the collapse of the scalar wave-packet. Given a one parameter family ${\cal S}[p]$ of solutions labeled by the parameter $p$ which controls the strength of interaction, it was expected that as $p$ is varied, there would be solutions with $p\rightarrow p_{weak}$ in which the collapsing wave-packet disperses again, and solutions with $p\rightarrow p_{strong}$ which have black hole formation. For a given family there was expected to be a critical value $p=p_{*}$ for which the first black hole appears as $p$ varies from the weak to the strong range. Do the smallest mass black holes have finite or infinitesimal mass? This issue would be of interest for censorship, since an infinitesimal mass would mean one could probe arbitrarily close to the singularity.

This problem was studied by Choptuik [@cho] numerically and some remarkable results were found. He confirmed that the family ${\cal S}[p]$ has dispersive solutions as well as those forming black holes, and a transition takes place from one class to the other at a critical $p=p_{*}$. The smallest black holes have infinitesimal mass. Near the critical region, the mass $M_{bh}$ of the black hole scales as $M_{bh}\approx (p-p_{*})^{\gamma}$, where $\gamma$ is a universal constant (i.e. same for 