The following example is out of the documentation of prooftrees (I suppose that an updated version of TeX Live is needed to make use of that package).
The problem is that the documentation’s .tex file has a gigantic preamble. What I need is a minimal example of the preamble to run that code so that I can start to experiment with the package:
begin{codcoeden}*[label=ptdefaults]{pkg{prooftrees}: default settings}
begin{prooftree}
{
to prove={{P vee (Q vee lnot R), P lif lnot R, Q lif lnot R} sststile{}{} lnot R}
}
[P vee (Q vee lnot R), just=Ass, checked
[P lif lnot R, just=Ass, checked
[Q lif lnot R, just=Ass, checked, name=last premise
[lnotlnot R, just={$lnot$ Conc}, name=not conc
[P, just={$vee$ Elim:!uuuu}
[lnot P, close={:!u,!c}]
[lnot R, close={:not conc,!c}, just={$lif$ Elim:!uuuu}]]
[Q vee lnot R
[Q, move by=1
[lnot Q, close={:!u,!c}]
[lnot R, close={:not conc,!c}, just={$lif$ Elim:last premise}]]
[lnot R, close={:not conc,!c}, move by=1, just={$vee$ Elim:!u}]]]]]]
end{prooftree}
end{codcoeden}
The tree looks like this in the end:
