let Al be QC-alphabet ; :: thesis: for X being Subset of (CQC-WFF Al) holds VERUM Al in Cn X
let X be Subset of (CQC-WFF Al); :: thesis: VERUM Al in Cn X
for T being Subset of (CQC-WFF Al) st T is being_a_theory & X c= T holds
VERUM Al in T ;
hence VERUM Al in Cn X by Def2; :: thesis: verum