let A be QC-alphabet ; :: thesis: for p being Element of CQC-WFF A
for x being bound_QC-variable of A st p is valid holds
Ex (x,p) is valid
let p be Element of CQC-WFF A; :: thesis: for x being bound_QC-variable of A st p is valid holds
Ex (x,p) is valid
let x be bound_QC-variable of A; :: thesis: ( p is valid implies Ex (x,p) is valid )
assume A1: p is valid ; :: thesis: Ex (x,p) is valid
p => (Ex (x,p)) is valid by Th15;
hence Ex (x,p) is valid by A1, CQC_THE1:65; :: thesis: verum