let S, T, U be RealNormSpace; for R being RestFunc of T,U st R /. (0. T) = 0. U holds
for L being Lipschitzian LinearOperator of S,T holds R * L is RestFunc of S,U
let R be RestFunc of T,U; ( R /. (0. T) = 0. U implies for L being Lipschitzian LinearOperator of S,T holds R * L is RestFunc of S,U )
assume A1:
R /. (0. T) = 0. U
; for L being Lipschitzian LinearOperator of S,T holds R * L is RestFunc of S,U
let L be Lipschitzian LinearOperator of S,T; R * L is RestFunc of S,U
consider K being Real such that
A2:
0 <= K
and
A3:
for h being Point of S holds ||.(L . h).|| <= K * ||.h.||
by LOPBAN_1:def 8;
A4:
dom L = the carrier of S
by FUNCT_2:def 1;
R is total
by NDIFF_1:def 5;
then
dom R = the carrier of T
by PARTFUN1:def 2;
then A5:
rng L c= dom R
;
A6:
0 + K < 1 + K
by XREAL_1:8;
A7:
now for e being Real st e > 0 holds
ex d1 being Real st
( d1 > 0 & ( for h being Point of S st h <> 0. S & ||.h.|| < d1 holds
(||.h.|| ") * ||.((R * L) /. h).|| < e ) )let e be
Real;
( e > 0 implies ex d1 being Real st
( d1 > 0 & ( for h being Point of S st h <> 0. S & ||.h.|| < d1 holds
(||.h.|| ") * ||.((R * L) /. h).|| < e ) ) )assume
e > 0
;
ex d1 being Real st
( d1 > 0 & ( for h being Point of S st h <> 0. S & ||.h.|| < d1 holds
(||.h.|| ") * ||.((R * L) /. h).|| < e ) )then A8:
0 / (1 + K) < e / (1 + K)
by A2, XREAL_1:74;
set e1 =
e / (1 + K);
consider d being
Real such that A9:
0 < d
and A10:
for
h being
Point of
T st
||.h.|| < d holds
||.(R /. h).|| <= (e / (1 + K)) * ||.h.||
by A1, A8, Th7;
set d1 =
d / (1 + K);
A11:
now for h being Point of S st h <> 0. S & ||.h.|| < d / (1 + K) holds
(||.h.|| ") * ||.((R * L) /. h).|| < elet h be
Point of
S;
( h <> 0. S & ||.h.|| < d / (1 + K) implies (||.h.|| ") * ||.((R * L) /. h).|| < e )assume that A12:
h <> 0. S
and A13:
||.h.|| < d / (1 + K)
;
(||.h.|| ") * ||.((R * L) /. h).|| < eA14:
||.(L . h).|| <= K * ||.h.||
by A3;
A15:
||.h.|| <> 0
by A12, NORMSP_0:def 5;
then A16:
||.h.|| > 0
by NORMSP_1:4;
then
K * ||.h.|| < (K + 1) * ||.h.||
by A6, XREAL_1:68;
then A17:
||.(L . h).|| < (K + 1) * ||.h.||
by A14, XXREAL_0:2;
(K + 1) * ||.h.|| < (K + 1) * (d / (1 + K))
by A2, A13, XREAL_1:68;
then
||.(L . h).|| < (K + 1) * (d / (1 + K))
by A17, XXREAL_0:2;
then
||.(L . h).|| < d
by A2, XCMPLX_1:87;
then A18:
||.(R /. (L . h)).|| <= (e / (1 + K)) * ||.(L . h).||
by A10;
A19:
R /. (L . h) =
R /. (L /. h)
.=
(R * L) /. h
by A4, A5, PARTFUN2:5
;
(e / (1 + K)) * ||.(L . h).|| < (e / (1 + K)) * ((K + 1) * ||.h.||)
by A8, A17, XREAL_1:68;
then
||.(R /. (L . h)).|| < (e / (1 + K)) * ((K + 1) * ||.h.||)
by A18, XXREAL_0:2;
then
(||.h.|| ") * ||.((R * L) /. h).|| < (||.h.|| ") * (((e / (1 + K)) * (K + 1)) * ||.h.||)
by A19, A16, XREAL_1:68;
then
(||.h.|| ") * ||.((R * L) /. h).|| < ((||.h.|| * (||.h.|| ")) * (e / (1 + K))) * (K + 1)
;
then
(||.h.|| ") * ||.((R * L) /. h).|| < (1 * (e / (1 + K))) * (K + 1)
by A15, XCMPLX_0:def 7;
hence
(||.h.|| ") * ||.((R * L) /. h).|| < e
by A2, XCMPLX_1:87;
verum end;
0 / (1 + K) < d / (1 + K)
by A2, A9, XREAL_1:74;
hence
ex
d1 being
Real st
(
d1 > 0 & ( for
h being
Point of
S st
h <> 0. S &
||.h.|| < d1 holds
(||.h.|| ") * ||.((R * L) /. h).|| < e ) )
by A11;
verum end;
dom (R * L) =
dom L
by A5, RELAT_1:27
.=
the carrier of S
by FUNCT_2:def 1
;
then
R * L is total
by PARTFUN1:def 2;
hence
R * L is RestFunc of S,U
by A7, NDIFF_1:23; verum