let A be QC-alphabet ; :: thesis: for p being Element of CQC-WFF A holds (p 'or' p) => p in TAUT A
let p be Element of CQC-WFF A; :: thesis: (p 'or' p) => p in TAUT A
( (p 'or' p) => (('not' p) => p) in TAUT A & (('not' p) => p) => p in TAUT A ) by Th5, CQC_THE1:42;
hence (p 'or' p) => p in TAUT A by LUKASI_1:3; :: thesis: verum