Goal:
    G : t  HI : invariants  x : VSet.elt
  ============================
   (VSet.In x (V G) ->
    lsp x x = Some 0 <->
    match lsp x x with
    | Some 0 => true
    | _ => false
    end = true)


DEBUG:Going to execute:
intro Hx
DEBUG LTAC Evaluated term: iff_forall