let x, y, z be bound_QC-variable; :: thesis: for p, q being Element of QC-WFF
for t, s being bound_QC-variable st All x,y,z,p = All t,s,q holds
( x = t & y = s & All z,p = q )
let p, q be Element of QC-WFF ; :: thesis: for t, s being bound_QC-variable st All x,y,z,p = All t,s,q holds
( x = t & y = s & All z,p = q )
let t, s be bound_QC-variable; :: thesis: ( All x,y,z,p = All t,s,q implies ( x = t & y = s & All z,p = q ) )
assume A1: All x,y,z,p = All t,s,q ; :: thesis: ( x = t & y = s & All z,p = q )
hence x = t by Th6; :: thesis: ( y = s & All z,p = q )
All y,z,p = All s,q by A1, Th6;
hence ( y = s & All z,p = q ) by Th6; :: thesis: verum