let r, s be real number ; :: thesis: ( r <= s implies ex B being Basis of Closed-Interval-TSpace r,s st
( ex f being ManySortedSet of st
for y being Point of (Closed-Interval-MSpace r,s) holds
( f . y = { (Ball y,(1 / n)) where n is Element of NAT : n <> 0 } & B = Union f ) & ( for X being Subset of (Closed-Interval-TSpace r,s) st X in B holds
X is connected ) ) )
set L = Closed-Interval-TSpace r,s;
set M = Closed-Interval-MSpace r,s;
A1:
Closed-Interval-TSpace r,s = TopSpaceMetr (Closed-Interval-MSpace r,s)
by TOPMETR:def 8;
assume A2:
r <= s
; :: thesis: ex B being Basis of Closed-Interval-TSpace r,s st
( ex f being ManySortedSet of st
for y being Point of (Closed-Interval-MSpace r,s) holds
( f . y = { (Ball y,(1 / n)) where n is Element of NAT : n <> 0 } & B = Union f ) & ( for X being Subset of (Closed-Interval-TSpace r,s) st X in B holds
X is connected ) )
defpred S1[ set , set ] means ex x being Point of (Closed-Interval-TSpace r,s) ex y being Point of (Closed-Interval-MSpace r,s) ex B being Basis of x st
( $1 = x & x = y & $2 = B & B = { (Ball y,(1 / n)) where n is Element of NAT : n <> 0 } );
A3:
for i being set st i in the carrier of (Closed-Interval-TSpace r,s) holds
ex j being set st S1[i,j]
proof
let i be
set ;
:: thesis: ( i in the carrier of (Closed-Interval-TSpace r,s) implies ex j being set st S1[i,j] )
assume
i in the
carrier of
(Closed-Interval-TSpace r,s)
;
:: thesis: ex j being set st S1[i,j]
then reconsider i =
i as
Point of
(Closed-Interval-TSpace r,s) ;
reconsider m =
i as
Point of
(Closed-Interval-MSpace r,s) by A1, TOPMETR:16;
consider B being
Basis of
i such that A4:
B = { (Ball m,(1 / n)) where n is Element of NAT : n <> 0 }
and
(
B is
countable & ex
f being
Function of
NAT ,
B st
for
n being
set st
n in NAT holds
ex
n' being
Element of
NAT st
(
n = n' &
f . n = Ball m,
(1 / (n' + 1)) ) )
by A1, FRECHET:11;
take
B
;
:: thesis: S1[i,B]
take
i
;
:: thesis: ex y being Point of (Closed-Interval-MSpace r,s) ex B being Basis of i st
( i = i & i = y & B = B & B = { (Ball y,(1 / n)) where n is Element of NAT : n <> 0 } )
take
m
;
:: thesis: ex B being Basis of i st
( i = i & i = m & B = B & B = { (Ball m,(1 / n)) where n is Element of NAT : n <> 0 } )
take
B
;
:: thesis: ( i = i & i = m & B = B & B = { (Ball m,(1 / n)) where n is Element of NAT : n <> 0 } )
thus
(
i = i &
i = m &
B = B &
B = { (Ball m,(1 / n)) where n is Element of NAT : n <> 0 } )
by A4;
:: thesis: verum
end;
consider f being ManySortedSet of such that
A5:
for i being set st i in the carrier of (Closed-Interval-TSpace r,s) holds
S1[i,f . i]
from PBOOLE:sch 3(A3);
for x being Element of (Closed-Interval-TSpace r,s) holds f . x is Basis of x
then reconsider B = Union f as Basis of Closed-Interval-TSpace r,s by TOPGEN_2:2;
take
B
; :: thesis: ( ex f being ManySortedSet of st
for y being Point of (Closed-Interval-MSpace r,s) holds
( f . y = { (Ball y,(1 / n)) where n is Element of NAT : n <> 0 } & B = Union f ) & ( for X being Subset of (Closed-Interval-TSpace r,s) st X in B holds
X is connected ) )
hereby :: thesis: for X being Subset of (Closed-Interval-TSpace r,s) st X in B holds
X is connected
take f =
f;
:: thesis: for x being Point of (Closed-Interval-MSpace r,s) holds
( f . x = { (Ball x,(1 / n)) where n is Element of NAT : n <> 0 } & B = Union f )let x be
Point of
(Closed-Interval-MSpace r,s);
:: thesis: ( f . x = { (Ball x,(1 / n)) where n is Element of NAT : n <> 0 } & B = Union f )the
carrier of
(Closed-Interval-MSpace r,s) =
[.r,s.]
by A2, TOPMETR:14
.=
the
carrier of
(Closed-Interval-TSpace r,s)
by A2, TOPMETR:25
;
then
S1[
x,
f . x]
by A5;
hence
(
f . x = { (Ball x,(1 / n)) where n is Element of NAT : n <> 0 } &
B = Union f )
;
:: thesis: verum
end;
let X be Subset of (Closed-Interval-TSpace r,s); :: thesis: ( X in B implies X is connected )
assume
X in B
; :: thesis: X is connected
then
X in union (rng f)
by CARD_3:def 4;
then consider Z being set such that
A6:
X in Z
and
A7:
Z in rng f
by TARSKI:def 4;
consider x being set such that
A8:
x in dom f
and
A9:
f . x = Z
by A7, FUNCT_1:def 5;
dom f = the carrier of (Closed-Interval-TSpace r,s)
by PARTFUN1:def 4;
then consider x1 being Point of (Closed-Interval-TSpace r,s), y being Point of (Closed-Interval-MSpace r,s), B1 being Basis of x1 such that
A10:
( x = x1 & x1 = y & f . x = B1 & B1 = { (Ball y,(1 / n)) where n is Element of NAT : n <> 0 } )
by A5, A8;
consider n being Element of NAT such that
A11:
X = Ball y,(1 / n)
and
A12:
n <> 0
by A6, A9, A10;
reconsider X1 = X as Subset of R^1 by PRE_TOPC:39;
0 < n
by A12;
then
1 / n > 0
by XREAL_1:141;
then
( Ball y,(1 / n) = [.r,s.] or Ball y,(1 / n) = [.r,(y + (1 / n)).[ or Ball y,(1 / n) = ].(y - (1 / n)),s.] or Ball y,(1 / n) = ].(y - (1 / n)),(y + (1 / n)).[ )
by A2, Th1;
then
X1 is connected
by A11, RCOMP_3:52;
hence
X is connected
by CONNSP_1:24; :: thesis: verum