| ⊦ validrefs(str, refs + refs0, ty, st) ∧ ¬ dups(refs) ∧ refs ≠ [] ∧ is_obj(str, refs .last, st) ∧ fs ' ∈ instfields(st[refs .last -- _type] .type .class) ∧ is_reftype(fs .type) ∧ refs0 ≠ [] → validrefs(str, refs + jvmref ', ty, st[refs .last -- fs ', refval(jvmref)]) |