let x, y be Element of [.0,1.]; ( 0 < x & x < 1 & 0 < y & y < 1 implies ((#R x) + (AffineMap ((- x),(x - 1)))) | ].0,1.[ is increasing )
assume ZZ:
( 0 < x & x < 1 & 0 < y & y < 1 )
; ((#R x) + (AffineMap ((- x),(x - 1)))) | ].0,1.[ is increasing
set f1 = #R x;
set f2 = AffineMap ((- x),(x - 1));
reconsider Y = ].0,1.[ as open Subset of REAL ;
set f = (#R x) + (AffineMap ((- x),(x - 1)));
set A = right_open_halfline 0;
G0:
right_open_halfline 0 c= dom (#R x)
by TAYLOR_1:def 4;
dom (#R x) = ].0,+infty.[
by TAYLOR_1:def 4;
then G1:
dom ((#R x) | (right_open_halfline 0)) = right_open_halfline 0
by RELAT_1:62;
K2:
AffineMap ((- x),(x - 1)) is_differentiable_on right_open_halfline 0
by FDIFF_1:26, LemmaAffine;
TR:
((#R x) | (right_open_halfline 0)) | (right_open_halfline 0) = (#R x) | (right_open_halfline 0)
by RELAT_1:72;
(#R x) | (right_open_halfline 0) is_differentiable_on right_open_halfline 0
then G2:
#R x is_differentiable_on right_open_halfline 0
by INTEGRA7:5;
then g2:
#R x is_differentiable_on Y
by FDIFF_1:26, XXREAL_1:247;
k2:
AffineMap ((- x),(x - 1)) is_differentiable_on Y
by FDIFF_1:26, LemmaAffine;
dom (AffineMap ((- x),(x - 1))) = REAL
by FUNCT_2:def 1;
then
right_open_halfline 0 c= (dom (#R x)) /\ (dom (AffineMap ((- x),(x - 1))))
by G0, XBOOLE_1:19;
then
right_open_halfline 0 c= dom ((#R x) + (AffineMap ((- x),(x - 1))))
by VALUED_1:def 1;
then
(#R x) + (AffineMap ((- x),(x - 1))) is_differentiable_on right_open_halfline 0
by K2, FDIFF_1:18, G2;
then ga:
(#R x) + (AffineMap ((- x),(x - 1))) is_differentiable_on Y
by FDIFF_1:26, XXREAL_1:247;
az: dom ((#R x) + (AffineMap ((- x),(x - 1)))) =
(dom (#R x)) /\ (dom (AffineMap ((- x),(x - 1))))
by VALUED_1:def 1
.=
(right_open_halfline 0) /\ (dom (AffineMap ((- x),(x - 1))))
by TAYLOR_1:def 4
.=
(right_open_halfline 0) /\ REAL
by FUNCT_2:def 1
.=
right_open_halfline 0
by XBOOLE_1:28
;
for y being Real st y in Y holds
0 < diff (((#R x) + (AffineMap ((- x),(x - 1)))),y)
proof
let y be
Real;
( y in Y implies 0 < diff (((#R x) + (AffineMap ((- x),(x - 1)))),y) )
assume Sa:
y in Y
;
0 < diff (((#R x) + (AffineMap ((- x),(x - 1)))),y)
then Sb:
(
0 < y &
y < 1 )
by XXREAL_1:4;
(
#R x is_differentiable_in y &
AffineMap (
(- x),
(x - 1))
is_differentiable_in y )
by k2, g2, Sa, FDIFF_1:9;
then H1:
diff (
((#R x) + (AffineMap ((- x),(x - 1)))),
y)
= (diff ((#R x),y)) + (diff ((AffineMap ((- x),(x - 1))),y))
by FDIFF_1:13;
(
#R x is_differentiable_in y &
diff (
(#R x),
y)
= x * (y #R (x - 1)) )
by TAYLOR_1:21, Sb;
then
diff (
(#R x),
y)
= x * (y to_power (x - 1))
by POWER:def 2, Sb;
then H3:
diff (
((#R x) + (AffineMap ((- x),(x - 1)))),
y) =
(x * (y to_power (x - 1))) - x
by H1, LemmaAffine
.=
x * ((y to_power (x - 1)) - 1)
;
x - 1
< 1
- 1
by ZZ, XREAL_1:9;
then
y to_power (x - 1) > y to_power 0
by POWER:40, Sb;
then
y to_power (x - 1) > 1
by POWER:24;
then
(y to_power (x - 1)) - 1
> 1
- 1
by XREAL_1:9;
hence
0 < diff (
((#R x) + (AffineMap ((- x),(x - 1)))),
y)
by XREAL_1:129, H3, ZZ;
verum
end;
hence
((#R x) + (AffineMap ((- x),(x - 1)))) | ].0,1.[ is increasing
by ROLLE:9, ga, az, XXREAL_1:247; verum