| ⊦ a ∈ st → (a ∈ dom st ∩ s ↔ a ∈ s) |
¬(a ∈ dom st ∩ s ↔ a ∈ s), a ∈ st ⊦
| ¬(a ∈ dom st ∩ s ↔ a ∈ s), a ∈ st ⊦ |
Used simplifier rules: Dom: ⊦ a ∈ dom st ↔ a ∈ st; int-c: ⊦ s ∩ s0 = s0 ∩ s; from specification set-union int-a: ⊦ (s ∩ s0) ∩ s1 = s ∩ s0 ∩ s1; from specification set-union ⊦ a ∈ s1 ∩ s2 ↔ a ∈ s1 ∧ a ∈ s2; (ws)
The following image shows the proof tree of sequent calculus. The proved goal is at the bottom. You can click on the nodes to view additional rules. See here for details on colors in a proof tree.