let X be non empty set ; :: thesis: for S being SigmaField of X
for f being with_the_same_dom Functional_Sequence of X,REAL
for F being SetSequence of S
for r being Real st ( for n being Nat holds F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) ) holds
meet (rng F) = (dom (f . 0)) /\ (great_eq_dom ((inf f),r))

let S be SigmaField of X; :: thesis: for f being with_the_same_dom Functional_Sequence of X,REAL
for F being SetSequence of S
for r being Real st ( for n being Nat holds F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) ) holds
meet (rng F) = (dom (f . 0)) /\ (great_eq_dom ((inf f),r))

let f be with_the_same_dom Functional_Sequence of X,REAL; :: thesis: for F being SetSequence of S
for r being Real st ( for n being Nat holds F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) ) holds
meet (rng F) = (dom (f . 0)) /\ (great_eq_dom ((inf f),r))

let F be SetSequence of S; :: thesis: for r being Real st ( for n being Nat holds F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) ) holds
meet (rng F) = (dom (f . 0)) /\ (great_eq_dom ((inf f),r))

let r be Real; :: thesis: ( ( for n being Nat holds F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) ) implies meet (rng F) = (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) )
set E = dom (f . 0);
assume A1: for n being Nat holds F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) ; :: thesis: meet (rng F) = (dom (f . 0)) /\ (great_eq_dom ((inf f),r))
now :: thesis: for x being object st x in meet (rng F) holds
x in (dom (f . 0)) /\ (great_eq_dom ((inf f),r))
let x be object ; :: thesis: ( x in meet (rng F) implies x in (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) )
assume A2: x in meet (rng F) ; :: thesis: x in (dom (f . 0)) /\ (great_eq_dom ((inf f),r))
then reconsider z = x as Element of X ;
A3: F . 0 = (dom (f . 0)) /\ (great_eq_dom ((f . 0),r)) by A1;
F . 0 in rng F by FUNCT_2:4;
then x in F . 0 by ;
then A4: x in dom (f . 0) by ;
then A5: x in dom (inf f) by MESFUNC8:def 3;
A6: now :: thesis: for n being Element of NAT holds r <= (R_EAL (f # z)) . n
let n be Element of NAT ; :: thesis: r <= (R_EAL (f # z)) . n
F . n in rng F by FUNCT_2:4;
then A7: z in F . n by ;
F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) by A1;
then x in great_eq_dom ((f . n),r) by ;
then r <= (f . n) . z by MESFUNC1:def 14;
hence r <= (R_EAL (f # z)) . n by SEQFUNC:def 10; :: thesis: verum
end;
for p being ExtReal st p in rng (R_EAL (f # z)) holds
r <= p
proof
let p be ExtReal; :: thesis: ( p in rng (R_EAL (f # z)) implies r <= p )
assume p in rng (R_EAL (f # z)) ; :: thesis: r <= p
then ex n being object st
( n in NAT & (R_EAL (f # z)) . n = p ) by FUNCT_2:11;
hence r <= p by A6; :: thesis: verum
end;
then r is LowerBound of rng (R_EAL (f # z)) by XXREAL_2:def 2;
then r <= inf (rng (R_EAL (f # z))) by XXREAL_2:def 4;
then r <= (inf f) . x by ;
then x in great_eq_dom ((inf f),r) by ;
hence x in (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) by ; :: thesis: verum
end;
then A8: meet (rng F) c= (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) ;
now :: thesis: for x being object st x in (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) holds
x in meet (rng F)
let x be object ; :: thesis: ( x in (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) implies x in meet (rng F) )
assume A9: x in (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) ; :: thesis: x in meet (rng F)
then reconsider z = x as Element of X ;
A10: x in dom (f . 0) by ;
x in great_eq_dom ((inf f),r) by ;
then A11: r <= (inf f) . z by MESFUNC1:def 14;
now :: thesis: for y being set st y in rng F holds
x in y
let y be set ; :: thesis: ( y in rng F implies x in y )
assume y in rng F ; :: thesis: x in y
then consider n being object such that
A12: n in NAT and
A13: y = F . n by FUNCT_2:11;
reconsider n = n as Element of NAT by A12;
A14: x in dom (f . n) by ;
x in dom (inf f) by ;
then A15: (inf f) . z = inf (rng (R_EAL (f # z))) by Th2;
(f . n) . z = (R_EAL (f # z)) . n by SEQFUNC:def 10;
then (f . n) . z >= inf (rng (R_EAL (f # z))) by ;
then r <= (f . n) . z by ;
then A16: x in great_eq_dom ((f . n),r) by ;
F . n = (dom (f . 0)) /\ (great_eq_dom ((f . n),r)) by A1;
hence x in y by ; :: thesis: verum
end;
hence x in meet (rng F) by SETFAM_1:def 1; :: thesis: verum
end;
then (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) c= meet (rng F) ;
hence meet (rng F) = (dom (f . 0)) /\ (great_eq_dom ((inf f),r)) by A8; :: thesis: verum