let B be Element of [:QC-Sub-WFF ,bound_QC-variables :]; for SQ being second_Q_comp of B st B is quantifiable holds
Sub_All B,SQ is Sub_universal
let SQ be second_Q_comp of B; ( B is quantifiable implies Sub_All B,SQ is Sub_universal )
assume A1:
B is quantifiable
; Sub_All B,SQ is Sub_universal
take
B
; SUBSTUT1:def 28 ex SQ being second_Q_comp of B st
( Sub_All B,SQ = Sub_All B,SQ & B is quantifiable )
take
SQ
; ( Sub_All B,SQ = Sub_All B,SQ & B is quantifiable )
thus
( Sub_All B,SQ = Sub_All B,SQ & B is quantifiable )
by A1; verum