let I1, I2 be Point of X; ( ( for T being DivSequence of A
for S being middle_volume_Sequence of f,T st delta T is convergent & lim (delta T) = 0 holds
( middle_sum (f,S) is convergent & lim (middle_sum (f,S)) = I1 ) ) & ( for T being DivSequence of A
for S being middle_volume_Sequence of f,T st delta T is convergent & lim (delta T) = 0 holds
( middle_sum (f,S) is convergent & lim (middle_sum (f,S)) = I2 ) ) implies I1 = I2 )
assume A2:
for T being DivSequence of A
for S being middle_volume_Sequence of f,T st delta T is convergent & lim (delta T) = 0 holds
( middle_sum (f,S) is convergent & lim (middle_sum (f,S)) = I1 )
; ( ex T being DivSequence of A ex S being middle_volume_Sequence of f,T st
( delta T is convergent & lim (delta T) = 0 & not ( middle_sum (f,S) is convergent & lim (middle_sum (f,S)) = I2 ) ) or I1 = I2 )
assume A3:
for T being DivSequence of A
for S being middle_volume_Sequence of f,T st delta T is convergent & lim (delta T) = 0 holds
( middle_sum (f,S) is convergent & lim (middle_sum (f,S)) = I2 )
; I1 = I2
consider T being DivSequence of A such that
A4:
( delta T is convergent & lim (delta T) = 0 )
by INTEGRA4:11;
set S = the middle_volume_Sequence of f,T;
thus I1 =
lim (middle_sum (f, the middle_volume_Sequence of f,T))
by A2, A4
.=
I2
by A3, A4
; verum