let x0 be Real; :: thesis: for f1, f2 being PartFunc of REAL ,REAL st f1 is_right_convergent_in x0 & lim_right f1,x0 = 0 & ( for r being Real st x0 < r holds
ex g being Real st
( g < r & x0 < g & g in dom (f1 (#) f2) ) ) & ex r being Real st
( 0 < r & f2 | ].x0,(x0 + r).[ is bounded ) holds
( f1 (#) f2 is_right_convergent_in x0 & lim_right (f1 (#) f2),x0 = 0 )
let f1, f2 be PartFunc of REAL ,REAL ; :: thesis: ( f1 is_right_convergent_in x0 & lim_right f1,x0 = 0 & ( for r being Real st x0 < r holds
ex g being Real st
( g < r & x0 < g & g in dom (f1 (#) f2) ) ) & ex r being Real st
( 0 < r & f2 | ].x0,(x0 + r).[ is bounded ) implies ( f1 (#) f2 is_right_convergent_in x0 & lim_right (f1 (#) f2),x0 = 0 ) )
assume A1:
( f1 is_right_convergent_in x0 & lim_right f1,x0 = 0 & ( for r being Real st x0 < r holds
ex g being Real st
( g < r & x0 < g & g in dom (f1 (#) f2) ) ) )
; :: thesis: ( for r being Real holds
( not 0 < r or not f2 | ].x0,(x0 + r).[ is bounded ) or ( f1 (#) f2 is_right_convergent_in x0 & lim_right (f1 (#) f2),x0 = 0 ) )
given r being Real such that A2:
( 0 < r & f2 | ].x0,(x0 + r).[ is bounded )
; :: thesis: ( f1 (#) f2 is_right_convergent_in x0 & lim_right (f1 (#) f2),x0 = 0 )
consider g being real number such that
A3:
for r1 being set st r1 in ].x0,(x0 + r).[ /\ (dom f2) holds
abs (f2 . r1) <= g
by A2, RFUNCT_1:90;
A4:
now let s be
Real_Sequence;
:: thesis: ( s is convergent & lim s = x0 & rng s c= (dom (f1 (#) f2)) /\ (right_open_halfline x0) implies ( (f1 (#) f2) /* s is convergent & lim ((f1 (#) f2) /* s) = 0 ) )assume A5:
(
s is
convergent &
lim s = x0 &
rng s c= (dom (f1 (#) f2)) /\ (right_open_halfline x0) )
;
:: thesis: ( (f1 (#) f2) /* s is convergent & lim ((f1 (#) f2) /* s) = 0 )then A6:
(
rng s c= dom (f1 (#) f2) &
rng s c= right_open_halfline x0 &
dom (f1 (#) f2) = (dom f1) /\ (dom f2) &
rng s c= dom f1 &
rng s c= dom f2 &
rng s c= (dom f1) /\ (right_open_halfline x0) &
rng s c= (dom f2) /\ (right_open_halfline x0) )
by Lm2;
x0 < x0 + r
by A2, Lm1;
then consider k being
Element of
NAT such that A7:
for
n being
Element of
NAT st
k <= n holds
s . n < x0 + r
by A5, Th2;
A8:
(
s ^\ k is
convergent &
lim (s ^\ k) = x0 )
by A5, SEQ_4:33;
set L =
right_open_halfline x0;
A9:
rng (s ^\ k) c= rng s
by VALUED_0:21;
then A10:
(
rng (s ^\ k) c= (dom f1) /\ (dom f2) &
rng (s ^\ k) c= dom f1 &
rng (s ^\ k) c= dom f2 &
rng (s ^\ k) c= (dom f1) /\ (right_open_halfline x0) &
rng (s ^\ k) c= right_open_halfline x0 &
rng (s ^\ k) c= (dom f2) /\ (right_open_halfline x0) )
by A6, XBOOLE_1:1;
then A11:
(
f1 /* (s ^\ k) is
convergent &
lim (f1 /* (s ^\ k)) = 0 )
by A1, A8, Def8;
now set t =
(abs g) + 1;
0 <= abs g
by COMPLEX1:132;
hence
0 < (abs g) + 1
;
:: thesis: for n being Element of NAT holds abs ((f2 /* (s ^\ k)) . n) < (abs g) + 1let n be
Element of
NAT ;
:: thesis: abs ((f2 /* (s ^\ k)) . n) < (abs g) + 1A12:
(s ^\ k) . n in rng (s ^\ k)
by VALUED_0:28;
then A13:
(
(s ^\ k) . n in dom f2 &
(s ^\ k) . n in right_open_halfline x0 )
by A10;
s . (n + k) < x0 + r
by A7, NAT_1:12;
then A14:
(s ^\ k) . n < x0 + r
by NAT_1:def 3;
(s ^\ k) . n in { g1 where g1 is Real : x0 < g1 }
by A13, XXREAL_1:230;
then
ex
g1 being
Real st
(
g1 = (s ^\ k) . n &
x0 < g1 )
;
then
(s ^\ k) . n in { g2 where g2 is Real : ( x0 < g2 & g2 < x0 + r ) }
by A14;
then
(s ^\ k) . n in ].x0,(x0 + r).[
by RCOMP_1:def 2;
then
(s ^\ k) . n in ].x0,(x0 + r).[ /\ (dom f2)
by A10, A12, XBOOLE_0:def 4;
then
abs (f2 . ((s ^\ k) . n)) <= g
by A3;
then A15:
abs ((f2 /* (s ^\ k)) . n) <= g
by A6, A9, FUNCT_2:185, XBOOLE_1:1;
g <= abs g
by ABSVALUE:11;
then
g < (abs g) + 1
by Lm1;
hence
abs ((f2 /* (s ^\ k)) . n) < (abs g) + 1
by A15, XXREAL_0:2;
:: thesis: verum end; then A16:
f2 /* (s ^\ k) is
bounded
by SEQ_2:15;
then A17:
(f1 /* (s ^\ k)) (#) (f2 /* (s ^\ k)) is
convergent
by A11, SEQ_2:39;
A18:
lim ((f1 /* (s ^\ k)) (#) (f2 /* (s ^\ k))) = 0
by A11, A16, SEQ_2:40;
A19:
(f1 /* (s ^\ k)) (#) (f2 /* (s ^\ k)) =
(f1 (#) f2) /* (s ^\ k)
by A10, RFUNCT_2:23
.=
((f1 (#) f2) /* s) ^\ k
by A6, VALUED_0:27
;
hence
(f1 (#) f2) /* s is
convergent
by A17, SEQ_4:35;
:: thesis: lim ((f1 (#) f2) /* s) = 0 thus
lim ((f1 (#) f2) /* s) = 0
by A17, A18, A19, SEQ_4:36;
:: thesis: verum end;
hence
f1 (#) f2 is_right_convergent_in x0
by A1, Def4; :: thesis: lim_right (f1 (#) f2),x0 = 0
hence
lim_right (f1 (#) f2),x0 = 0
by A4, Def8; :: thesis: verum