| ⊦ ((btree(rp, r, adr, height, false, ri, iast, as, alladrs, ok) * true))(zh) → ((btree(rp, null, adr, height, false, ri, iast, as, alladrs, ok) * true))(zh) |
((btree(rp, r, adr, height, false, ri, iast, as, alladrs, ok) * true))(zh) ⊦ ((btree(rp, null, adr, height, false, ri, iast, as, alladrs, ok) * true))(zh)