let A be QC-alphabet ; :: thesis: for p being Element of CQC-WFF A holds ('not' (VERUM A)) => p in TAUT A

let p be Element of CQC-WFF A; :: thesis: ('not' (VERUM A)) => p in TAUT A

(VERUM A) => (('not' (VERUM A)) => p) in TAUT A by CQC_THE1:43;

hence ('not' (VERUM A)) => p in TAUT A by CQC_THE1:41, CQC_THE1:46; :: thesis: verum

let p be Element of CQC-WFF A; :: thesis: ('not' (VERUM A)) => p in TAUT A

(VERUM A) => (('not' (VERUM A)) => p) in TAUT A by CQC_THE1:43;

hence ('not' (VERUM A)) => p in TAUT A by CQC_THE1:41, CQC_THE1:46; :: thesis: verum