take
[ the object , the object , the object , the object ]
; [ the object , the object , the object , the object ] is quadruple
take
the object
; XTUPLE_0:def 9 ex x2, x3, x4 being object st [ the object , the object , the object , the object ] = [ the object ,x2,x3,x4]
take
the object
; ex x3, x4 being object st [ the object , the object , the object , the object ] = [ the object , the object ,x3,x4]
take
the object
; ex x4 being object st [ the object , the object , the object , the object ] = [ the object , the object , the object ,x4]
take
the object
; [ the object , the object , the object , the object ] = [ the object , the object , the object , the object ]
thus
[ the object , the object , the object , the object ] = [ the object , the object , the object , the object ]
; verum