let A be QC-alphabet ; for B being Element of [:(QC-Sub-WFF A),(bound_QC-variables A):]
for SQ being second_Q_comp of B st B is quantifiable holds
Sub_All (B,SQ) is Sub_universal
let B be Element of [:(QC-Sub-WFF A),(bound_QC-variables A):]; 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