| ⊦ tree.fid:= fid = fnode(fid), tree.dir? |
⊦ tree.dir? ↔ ¬(∃ fid. tree = fnode(fid))
⊦ fnode(fid).fid:= fid0 = fnode(fid0)
Used simplifier rules: fnode-elim-strong: ⊦ tree.dir? ↔ ¬(∃ fid. tree = fnode(fid));%setfid: ⊦ fnode(fid).fid:= fid0 = fnode(fid0);% ⊦ fnode(fid) = fnode(fid0) ↔ fid = fid0; (s)