| ⊦ p ∈ tree ↔ p = ε, tree.dir? |
⊦ ε ∈ tree
⊦ tree.dir? ↔ ¬(∃ fid. tree = fnode(fid))
⊦ p ∈ fnode(fid) ↔ p = ε
Used simplifier rules: nil-in: ⊦ ε ∈ tree;%fnode-elim-strong: ⊦ tree.dir? ↔ ¬(∃ fid. tree = fnode(fid));%fnode-notin: ⊦ p ∈ fnode(fid) ↔ p = ε;