let X be set ; :: thesis: for F being Field_Subset of X
for M being Measure of F
for Sets being SetSequence of X
for Cvr being Covering of Sets,F holds inf (Svc M,(union (rng Sets))) <= SUM (Volume M,Cvr)

let F be Field_Subset of X; :: thesis: for M being Measure of F
for Sets being SetSequence of X
for Cvr being Covering of Sets,F holds inf (Svc M,(union (rng Sets))) <= SUM (Volume M,Cvr)

let M be Measure of F; :: thesis: for Sets being SetSequence of X
for Cvr being Covering of Sets,F holds inf (Svc M,(union (rng Sets))) <= SUM (Volume M,Cvr)

let Sets be SetSequence of X; :: thesis: for Cvr being Covering of Sets,F holds inf (Svc M,(union (rng Sets))) <= SUM (Volume M,Cvr)
let Cvr be Covering of Sets,F; :: thesis: inf (Svc M,(union (rng Sets))) <= SUM (Volume M,Cvr)
set Q = SUM (vol M,(On Cvr));
for x being ext-real number st x in rng (Ser (vol M,(On Cvr))) holds
ex y being ext-real number st
( y in rng (Ser (Volume M,Cvr)) & x <= y )
proof
let x be ext-real number ; :: thesis: ( x in rng (Ser (vol M,(On Cvr))) implies ex y being ext-real number st
( y in rng (Ser (Volume M,Cvr)) & x <= y ) )

assume x in rng (Ser (vol M,(On Cvr))) ; :: thesis: ex y being ext-real number st
( y in rng (Ser (Volume M,Cvr)) & x <= y )

then consider n being Element of NAT such that
A4: x = (Ser (vol M,(On Cvr))) . n by FUNCT_2:190;
consider m being Nat such that
A5: for Sets being SetSequence of X
for G being Covering of Sets,F holds (Partial_Sums (vol M,(On G))) . n <= (Partial_Sums (Volume M,G)) . m by Th15x;
B5: for Sets being SetSequence of X
for G being Covering of Sets,F holds (Ser (vol M,(On G))) . n <= (Ser (Volume M,G)) . m
proof
let Sets be SetSequence of X; :: thesis: for G being Covering of Sets,F holds (Ser (vol M,(On G))) . n <= (Ser (Volume M,G)) . m
let G be Covering of Sets,F; :: thesis: (Ser (vol M,(On G))) . n <= (Ser (Volume M,G)) . m
(Partial_Sums (vol M,(On G))) . n <= (Partial_Sums (Volume M,G)) . m by A5;
then (Ser (vol M,(On G))) . n <= (Partial_Sums (Volume M,G)) . m by Lem12;
hence (Ser (vol M,(On G))) . n <= (Ser (Volume M,G)) . m by Lem12; :: thesis: verum
end;
take (Ser (Volume M,Cvr)) . m ; :: thesis: ( (Ser (Volume M,Cvr)) . m in rng (Ser (Volume M,Cvr)) & x <= (Ser (Volume M,Cvr)) . m )
m in NAT by ORDINAL1:def 13;
hence ( (Ser (Volume M,Cvr)) . m in rng (Ser (Volume M,Cvr)) & x <= (Ser (Volume M,Cvr)) . m ) by A4, B5, FUNCT_2:6; :: thesis: verum
end;
then A6: SUM (vol M,(On Cvr)) <= SUM (Volume M,Cvr) by XXREAL_2:63;
SUM (vol M,(On Cvr)) in Svc M,(union (rng Sets)) by Def8;
then inf (Svc M,(union (rng Sets))) <= SUM (vol M,(On Cvr)) by XXREAL_2:3;
hence inf (Svc M,(union (rng Sets))) <= SUM (Volume M,Cvr) by A6, XXREAL_0:2; :: thesis: verum