set E = the carrier of R^1;
let T be non empty interval SubSpace of R^1 ; for P, Q being continuous Function of I[01],T holds R1Homotopy (P,Q) is continuous
let P, Q be continuous Function of I[01],T; R1Homotopy (P,Q) is continuous
set F = R1Homotopy (P,Q);
set PI = [:P,(id I[01]):];
set QI = [:Q,(id I[01]):];
defpred S1[ Element of the carrier of R^1, Element of the carrier of I[01], set ] means $3 = (1 - $2) * $1;
defpred S2[ Element of the carrier of R^1, Element of the carrier of I[01], set ] means $3 = $2 * $1;
A1:
the carrier of T is Subset of R^1
by TSEP_1:1;
then reconsider G = R1Homotopy (P,Q) as Function of [:I[01],I[01]:],R^1 by FUNCT_2:7;
reconsider P1 = P, Q1 = Q as Function of I[01],R^1 by A1, FUNCT_2:7;
reconsider P1 = P1, Q1 = Q1 as continuous Function of I[01],R^1 by PRE_TOPC:26;
set P1I = [:P1,(id I[01]):];
set Q1I = [:Q1,(id I[01]):];
A2:
for x being Element of the carrier of R^1
for y being Element of the carrier of I[01] ex z being Element of the carrier of R^1 st S1[x,y,z]
consider Pa being Function of [: the carrier of R^1, the carrier of I[01]:], the carrier of R^1 such that
A3:
for x being Element of the carrier of R^1
for i being Element of the carrier of I[01] holds S1[x,i,Pa . (x,i)]
from BINOP_1:sch 3(A2);
A4:
for x being Element of the carrier of R^1
for y being Element of the carrier of I[01] ex z being Element of the carrier of R^1 st S2[x,y,z]
consider Pb being Function of [: the carrier of R^1, the carrier of I[01]:], the carrier of R^1 such that
A5:
for x being Element of the carrier of R^1
for i being Element of the carrier of I[01] holds S2[x,i,Pb . (x,i)]
from BINOP_1:sch 3(A4);
reconsider Pa = Pa, Pb = Pb as Function of [:R^1,I[01]:],R^1 by Lm3;
A6:
Pb is continuous
by A5, Th7;
Pa is continuous
by A3, Th6;
then consider g being Function of [:I[01],I[01]:],R^1 such that
A7:
for p being Point of [:I[01],I[01]:]
for r1, r2 being Real st (Pa * [:P1,(id I[01]):]) . p = r1 & (Pb * [:Q1,(id I[01]):]) . p = r2 holds
g . p = r1 + r2
and
A8:
g is continuous
by A6, JGRAPH_2:19;
A9:
for p being Point of [:I[01],I[01]:] holds G . p = ((Pa * [:P1,(id I[01]):]) . p) + ((Pb * [:Q1,(id I[01]):]) . p)
proof
A10:
dom Q = the
carrier of
I[01]
by FUNCT_2:def 1;
A11:
dom P = the
carrier of
I[01]
by FUNCT_2:def 1;
let p be
Point of
[:I[01],I[01]:];
G . p = ((Pa * [:P1,(id I[01]):]) . p) + ((Pb * [:Q1,(id I[01]):]) . p)
consider s,
t being
Point of
I[01] such that A12:
p = [s,t]
by BORSUK_1:10;
reconsider a1 =
P . s,
b1 =
Q . s as
Point of
R^1 by PRE_TOPC:25;
A13:
P . s in the
carrier of
T
;
A14:
(R1Homotopy (P,Q)) . (
s,
t)
= ((1 - t) * a1) + (t * b1)
by Def4;
A15:
Q . s in the
carrier of
T
;
A16:
(id I[01]) . t = t
by FUNCT_1:18;
A17:
(Pb * [:Q,(id I[01]):]) . p =
Pb . ([:Q,(id I[01]):] . (s,t))
by A12, FUNCT_2:15
.=
Pb . (
(Q . s),
t)
by A10, A16, Lm4, FUNCT_3:def 8
.=
t * (Q . s)
by A1, A5, A15
;
(Pa * [:P,(id I[01]):]) . p =
Pa . ([:P,(id I[01]):] . (s,t))
by A12, FUNCT_2:15
.=
Pa . (
(P . s),
t)
by A11, A16, Lm4, FUNCT_3:def 8
.=
(1 - t) * (P . s)
by A1, A3, A13
;
hence
G . p = ((Pa * [:P1,(id I[01]):]) . p) + ((Pb * [:Q1,(id I[01]):]) . p)
by A12, A17, A14;
verum
end;
for p being Point of [:I[01],I[01]:] holds G . p = g . p
hence
R1Homotopy (P,Q) is continuous
by A8, FUNCT_2:63, PRE_TOPC:27; verum