let x0 be Real; :: thesis: for f1, f2 being PartFunc of REAL ,REAL st f1 is_right_convergent_in x0 & f2 is_right_convergent_in x0 & ( for r being Real st x0 < r holds
ex g being Real st
( g < r & x0 < g & g in dom (f1 (#) f2) ) ) holds
( f1 (#) f2 is_right_convergent_in x0 & lim_right (f1 (#) f2),x0 = (lim_right f1,x0) * (lim_right f2,x0) )
let f1, f2 be PartFunc of REAL ,REAL ; :: thesis: ( f1 is_right_convergent_in x0 & f2 is_right_convergent_in x0 & ( for r being Real st x0 < r holds
ex g being Real st
( g < r & x0 < g & g in dom (f1 (#) f2) ) ) implies ( f1 (#) f2 is_right_convergent_in x0 & lim_right (f1 (#) f2),x0 = (lim_right f1,x0) * (lim_right f2,x0) ) )
assume A1:
( f1 is_right_convergent_in x0 & f2 is_right_convergent_in x0 & ( for r being Real st x0 < r holds
ex g being Real st
( g < r & x0 < g & g in dom (f1 (#) f2) ) ) )
; :: thesis: ( f1 (#) f2 is_right_convergent_in x0 & lim_right (f1 (#) f2),x0 = (lim_right f1,x0) * (lim_right f2,x0) )
A2:
now A3:
(
lim_right f1,
x0 = lim_right f1,
x0 &
lim_right f2,
x0 = lim_right f2,
x0 )
;
let seq be
Real_Sequence;
:: thesis: ( seq is convergent & lim seq = x0 & rng seq c= (dom (f1 (#) f2)) /\ (right_open_halfline x0) implies ( (f1 (#) f2) /* seq is convergent & lim ((f1 (#) f2) /* seq) = (lim_right f1,x0) * (lim_right f2,x0) ) )assume A4:
(
seq is
convergent &
lim seq = x0 &
rng seq c= (dom (f1 (#) f2)) /\ (right_open_halfline x0) )
;
:: thesis: ( (f1 (#) f2) /* seq is convergent & lim ((f1 (#) f2) /* seq) = (lim_right f1,x0) * (lim_right f2,x0) )then A5:
(
rng seq c= dom (f1 (#) f2) &
rng seq c= right_open_halfline x0 &
dom (f1 (#) f2) = (dom f1) /\ (dom f2) &
rng seq c= (dom f1) /\ (right_open_halfline x0) &
rng seq c= (dom f2) /\ (right_open_halfline x0) )
by Lm2;
then A6:
(
f1 /* seq is
convergent &
lim (f1 /* seq) = lim_right f1,
x0 )
by A1, A3, A4, Def8;
A7:
(
f2 /* seq is
convergent &
lim (f2 /* seq) = lim_right f2,
x0 )
by A1, A3, A4, A5, Def8;
A8:
(f1 /* seq) (#) (f2 /* seq) = (f1 (#) f2) /* seq
by A5, RFUNCT_2:23;
hence
(f1 (#) f2) /* seq is
convergent
by A6, A7, SEQ_2:28;
:: thesis: lim ((f1 (#) f2) /* seq) = (lim_right f1,x0) * (lim_right f2,x0)thus
lim ((f1 (#) f2) /* seq) = (lim_right f1,x0) * (lim_right f2,x0)
by A6, A7, A8, SEQ_2:29;
:: thesis: verum end;
hence
f1 (#) f2 is_right_convergent_in x0
by A1, Def4; :: thesis: lim_right (f1 (#) f2),x0 = (lim_right f1,x0) * (lim_right f2,x0)
hence
lim_right (f1 (#) f2),x0 = (lim_right f1,x0) * (lim_right f2,x0)
by A2, Def8; :: thesis: verum