(*TODO: Move to ev_semantics*)
    Definition in_free_list (b : block) ofs xs :=
      exists x, List.In x xs /\
           let '(b', lo, hi) := x in
           b = b' /\
           (lo <= ofs < hi)%Z.

Lemma step_thread_det: forall tp m tid (cnt: containsThread tp tid) tp' m' tp'' m'' ev ev' (Hcmpt: mem_compatible tp m) (Hstep: threadStep cnt Hcmpt tp' m' ev) (Hstep': threadStep cnt Hcmpt tp'' m'' ev'), tp' = tp'' /\ m' = m'' /\ ev = ev'.