let A be QC-alphabet ; :: thesis: for p being Element of CQC-WFF A holds p => p in TAUT A
let p be Element of CQC-WFF A; :: thesis: p => p in TAUT A
( (('not' p) => p) => p in TAUT A & p => (('not' p) => p) in TAUT A ) by CQC_THE1:42, CQC_THE1:43;
hence p => p in TAUT A by Th3; :: thesis: verum