adr ∈ ri -- key, ri.lebs ⊆ ns ⊦ adr.lnum ∈ ns, (ri -- key).lebs ⊆ ri.lebs
Used simplifier rules: lebs-index: ⊦ n ∈ ri.lebs ↔ (∃ adr. adr.lnum = n ∧ adr ∈ ri);