let u be Element of (TOP-REAL 3); u = |[(u . 1),(u . 2),(u . 3)]|
thus u =
|[(u `1),(u `2),(u `3)]|
by EUCLID_5:3
.=
|[(u . 1),(u `2),(u `3)]|
by EUCLID_5:def 1
.=
|[(u . 1),(u . 2),(u `3)]|
by EUCLID_5:def 2
.=
|[(u . 1),(u . 2),(u . 3)]|
by EUCLID_5:def 3
; verum