let x0 be Real; :: thesis: for f being PartFunc of REAL ,REAL st f is_convergent_in x0 & f " {0 } = {} & lim f,x0 <> 0 holds
( f ^ is_convergent_in x0 & lim (f ^ ),x0 = (lim f,x0) " )
let f be PartFunc of REAL ,REAL ; :: thesis: ( f is_convergent_in x0 & f " {0 } = {} & lim f,x0 <> 0 implies ( f ^ is_convergent_in x0 & lim (f ^ ),x0 = (lim f,x0) " ) )
assume A1:
( f is_convergent_in x0 & f " {0 } = {} & lim f,x0 <> 0 )
; :: thesis: ( f ^ is_convergent_in x0 & lim (f ^ ),x0 = (lim f,x0) " )
then A2: dom f =
(dom f) \ (f " {0 })
.=
dom (f ^ )
by RFUNCT_1:def 8
;
then A3:
for r1, r2 being Real st r1 < x0 & x0 < r2 holds
ex g1, g2 being Real st
( r1 < g1 & g1 < x0 & g1 in dom (f ^ ) & g2 < r2 & x0 < g2 & g2 in dom (f ^ ) )
by A1, Def1;
A4:
now let seq be
Real_Sequence;
:: thesis: ( seq is convergent & lim seq = x0 & rng seq c= (dom (f ^ )) \ {x0} implies ( (f ^ ) /* seq is convergent & lim ((f ^ ) /* seq) = (lim f,x0) " ) )assume A5:
(
seq is
convergent &
lim seq = x0 &
rng seq c= (dom (f ^ )) \ {x0} )
;
:: thesis: ( (f ^ ) /* seq is convergent & lim ((f ^ ) /* seq) = (lim f,x0) " )then A6:
(
f /* seq is
convergent &
lim (f /* seq) = lim f,
x0 )
by A1, A2, Def4;
A7:
rng seq c= dom f
by A2, A5, XBOOLE_1:1;
A8:
(f /* seq) " = (f ^ ) /* seq
by A5, RFUNCT_2:27, XBOOLE_1:1;
hence
(f ^ ) /* seq is
convergent
by A1, A2, A6, A7, RFUNCT_2:26, SEQ_2:35;
:: thesis: lim ((f ^ ) /* seq) = (lim f,x0) " thus
lim ((f ^ ) /* seq) = (lim f,x0) "
by A1, A2, A6, A7, A8, RFUNCT_2:26, SEQ_2:36;
:: thesis: verum end;
hence
f ^ is_convergent_in x0
by A3, Def1; :: thesis: lim (f ^ ),x0 = (lim f,x0) "
hence
lim (f ^ ),x0 = (lim f,x0) "
by A4, Def4; :: thesis: verum