let x, y be bound_QC-variable; for p, q being Element of QC-WFF st All x,p = All y,q holds
( x = y & p = q )
let p, q be Element of QC-WFF ; ( All x,p = All y,q implies ( x = y & p = q ) )
A1:
( (<*[3,0 ]*> ^ <*x*>) ^ (@ p) = <*[3,0 ]*> ^ (<*x*> ^ (@ p)) & (<*[3,0 ]*> ^ <*y*>) ^ (@ q) = <*[3,0 ]*> ^ (<*y*> ^ (@ q)) )
by FINSEQ_1:45;
A2:
( (<*x*> ^ (@ p)) . 1 = x & (<*y*> ^ (@ q)) . 1 = y )
by FINSEQ_1:58;
assume A3:
All x,p = All y,q
; ( x = y & p = q )
hence
x = y
by A1, A2, FINSEQ_1:46; p = q
<*x*> ^ (@ p) = <*y*> ^ (@ q)
by A3, A1, FINSEQ_1:46;
hence
p = q
by A2, FINSEQ_1:46; verum