public static Keyword tryLookupGroundAssertionsProof(ControlFrame frame) {
    if (frame.proposition.kind == Logic.KWD_ISA) {
      if (((Boolean)(Logic.$REVERSEPOLARITYp$.get())).booleanValue()) {
        return (ControlFrame.tryScanPropositionsProof(frame));
      }
      return (ControlFrame.tryIsaPropositionProof(frame));
    }
    else {
      return (ControlFrame.tryScanPropositionsProof(frame));
    }
  }