| n < # apebs, ubi-io-inv(apebs) ⊦ ⟨aubi_io_isbad#(n, apebs; ; isbad, err)⟩ true |
n < # apebs, ubi-io-inv(apebs) ⊦ ⟨if ubi-io-isbad-pre(n, apebs) then {fail_or_success#(; ; err); if err = ESUCCESS then isbad := apebs[n].bad else isbad := ?} else abort⟩ true
Used simplifier rules: isbad: ⊦ ;