let p be Element of CQC-WFF ; :: thesis: (('not' p) => ('not' VERUM)) => p in TAUT
( ('not' p) => (('not' VERUM) => p) in TAUT & (('not' p) => (('not' VERUM) => p)) => ((('not' p) => ('not' VERUM)) => (('not' p) => p)) in TAUT ) by Th11, Th12, Th13;
then A1: (('not' p) => ('not' VERUM)) => (('not' p) => p) in TAUT by CQC_THE1:46;
(('not' p) => p) => p in TAUT by CQC_THE1:42;
hence (('not' p) => ('not' VERUM)) => p in TAUT by A1, Th3; :: thesis: verum