let A be non empty set ; :: thesis: for p, q being Element of CQC-WFF
for J being interpretation of A holds J |= (p '&' q) => (q '&' p)
let p, q be Element of CQC-WFF ; :: thesis: for J being interpretation of A holds J |= (p '&' q) => (q '&' p)
let J be interpretation of A; :: thesis: J |= (p '&' q) => (q '&' p)
let v be Element of Valuations_in A; :: according to VALUAT_1:def 8 :: thesis: J,v |= (p '&' q) => (q '&' p)
thus J,v |= (p '&' q) => (q '&' p) by Th45; :: thesis: verum