let M be non empty Reflexive symmetric triangle MetrStruct ; ( M is complete implies for a being Point of M st ex b being Point of M st dist (a,b) <> 0 holds
for X being infinite set holds
( WellSpace (a,X) is complete & ex S being non-empty pointwise_bounded SetSequence of (WellSpace (a,X)) st
( S is closed & S is non-ascending & meet S is empty ) ) )
assume A1:
M is complete
; for a being Point of M st ex b being Point of M st dist (a,b) <> 0 holds
for X being infinite set holds
( WellSpace (a,X) is complete & ex S being non-empty pointwise_bounded SetSequence of (WellSpace (a,X)) st
( S is closed & S is non-ascending & meet S is empty ) )
let a be Point of M; ( ex b being Point of M st dist (a,b) <> 0 implies for X being infinite set holds
( WellSpace (a,X) is complete & ex S being non-empty pointwise_bounded SetSequence of (WellSpace (a,X)) st
( S is closed & S is non-ascending & meet S is empty ) ) )
assume
ex b being Point of M st dist (a,b) <> 0
; for X being infinite set holds
( WellSpace (a,X) is complete & ex S being non-empty pointwise_bounded SetSequence of (WellSpace (a,X)) st
( S is closed & S is non-ascending & meet S is empty ) )
then consider b being Point of M such that
A2:
dist (a,b) <> 0
;
let X be infinite set ; ( WellSpace (a,X) is complete & ex S being non-empty pointwise_bounded SetSequence of (WellSpace (a,X)) st
( S is closed & S is non-ascending & meet S is empty ) )
set W = WellSpace (a,X);
thus
WellSpace (a,X) is complete
by A1, Th41; ex S being non-empty pointwise_bounded SetSequence of (WellSpace (a,X)) st
( S is closed & S is non-ascending & meet S is empty )
set TW = TopSpaceMetr (WellSpace (a,X));
consider f being sequence of X such that
A3:
f is one-to-one
by DICKSON:3;
defpred S1[ object , object ] means $2 = [(f . $1),b];
A4:
b <> a
by A2, METRIC_1:1;
A5:
for x being object st x in NAT holds
ex y being object st
( y in the carrier of (TopSpaceMetr (WellSpace (a,X))) & S1[x,y] )
proof
let x be
object ;
( x in NAT implies ex y being object st
( y in the carrier of (TopSpaceMetr (WellSpace (a,X))) & S1[x,y] ) )
assume
x in NAT
;
ex y being object st
( y in the carrier of (TopSpaceMetr (WellSpace (a,X))) & S1[x,y] )
then
x in dom f
by FUNCT_2:def 1;
then A6:
f . x in rng f
by FUNCT_1:def 3;
take
[(f . x),b]
;
( [(f . x),b] in the carrier of (TopSpaceMetr (WellSpace (a,X))) & S1[x,[(f . x),b]] )
thus
(
[(f . x),b] in the
carrier of
(TopSpaceMetr (WellSpace (a,X))) &
S1[
x,
[(f . x),b]] )
by A4, A6, Th37;
verum
end;
consider s being sequence of the carrier of (TopSpaceMetr (WellSpace (a,X))) such that
A7:
for x being object st x in NAT holds
S1[x,s . x]
from FUNCT_2:sch 1(A5);
deffunc H1( object ) -> set = {(s . $1)};
A8:
for x being object st x in NAT holds
H1(x) in bool the carrier of (TopSpaceMetr (WellSpace (a,X)))
consider S being SetSequence of (TopSpaceMetr (WellSpace (a,X))) such that
A10:
for x being object st x in NAT holds
S . x = H1(x)
from FUNCT_2:sch 2(A8);
A11:
now for x1, x2 being object st x1 in NAT & x2 in NAT & S . x1 = S . x2 holds
x1 = x2let x1,
x2 be
object ;
( x1 in NAT & x2 in NAT & S . x1 = S . x2 implies x1 = x2 )assume that A12:
x1 in NAT
and A13:
x2 in NAT
and A14:
S . x1 = S . x2
;
x1 = x2A15:
S . x2 = {(s . x2)}
by A10, A13;
A16:
s . x1 = [(f . x1),b]
by A7, A12;
A17:
s . x1 in {(s . x1)}
by TARSKI:def 1;
A18:
s . x2 = [(f . x2),b]
by A7, A13;
S . x1 = {(s . x1)}
by A10, A12;
then
s . x1 = s . x2
by A14, A15, A17, TARSKI:def 1;
then
f . x1 = f . x2
by A16, A18, XTUPLE_0:1;
hence
x1 = x2
by A3, A12, A13, FUNCT_2:19;
verum end;
reconsider rngs = rng s as Subset of (TopSpaceMetr (WellSpace (a,X))) ;
set F = { {x} where x is Element of (TopSpaceMetr (WellSpace (a,X))) : x in rngs } ;
reconsider F = { {x} where x is Element of (TopSpaceMetr (WellSpace (a,X))) : x in rngs } as Subset-Family of (TopSpaceMetr (WellSpace (a,X))) by RELSET_2:16;
dist (a,b) > 0
by A2, METRIC_1:5;
then A19:
2 * (dist (a,b)) > 0
by XREAL_1:129;
A20:
rng S c= F
then
S is non-empty
by FUNCT_1:def 9;
then consider R being non-empty closed SetSequence of (TopSpaceMetr (WellSpace (a,X))) such that
A24:
R is non-ascending
and
A25:
( F is locally_finite & S is one-to-one implies meet R = {} )
and
A26:
for i being Nat ex Si being Subset-Family of (TopSpaceMetr (WellSpace (a,X))) st
( R . i = Cl (union Si) & Si = { (S . j) where j is Element of NAT : j >= i } )
by A20, Th23;
reconsider R9 = R as non-empty SetSequence of (WellSpace (a,X)) ;
A27:
now for x, y being Point of (WellSpace (a,X)) st x in rngs & y in rngs & x <> y holds
dist (x,y) = 2 * (dist (a,b))let x,
y be
Point of
(WellSpace (a,X));
( x in rngs & y in rngs & x <> y implies dist (x,y) = 2 * (dist (a,b)) )assume that A28:
x in rngs
and A29:
y in rngs
and A30:
x <> y
;
dist (x,y) = 2 * (dist (a,b))consider y1 being
object such that A31:
y1 in dom s
and A32:
s . y1 = y
by A29, FUNCT_1:def 3;
A33:
y = [(f . y1),b]
by A7, A31, A32;
consider x1 being
object such that A34:
x1 in dom s
and A35:
s . x1 = x
by A28, FUNCT_1:def 3;
x = [(f . x1),b]
by A7, A34, A35;
then
(well_dist (a,X)) . (
x,
y)
= (dist (b,a)) + (dist (a,b))
by A30, A33, Def10;
hence
dist (
x,
y)
= 2
* (dist (a,b))
;
verum end;
now for i being Nat holds R9 . i is bounded let i be
Nat;
R9 . i is bounded consider Si being
Subset-Family of
(TopSpaceMetr (WellSpace (a,X))) such that A36:
R . i = Cl (union Si)
and A37:
Si = { (S . j) where j is Element of NAT : j >= i }
by A26;
reconsider SI =
union Si as
Subset of
(WellSpace (a,X)) ;
now for x, y being Point of (WellSpace (a,X)) st x in SI & y in SI holds
dist (x,y) <= 2 * (dist (a,b))let x,
y be
Point of
(WellSpace (a,X));
( x in SI & y in SI implies dist (x,y) <= 2 * (dist (a,b)) )assume that A38:
x in SI
and A39:
y in SI
;
dist (x,y) <= 2 * (dist (a,b))consider xS being
set such that A40:
x in xS
and A41:
xS in Si
by A38, TARSKI:def 4;
consider j1 being
Element of
NAT such that A42:
xS = S . j1
and
j1 >= i
by A37, A41;
A43:
S . j1 = {(s . j1)}
by A10;
A44:
dom s = NAT
by FUNCT_2:def 1;
then
s . j1 in rngs
by FUNCT_1:def 3;
then A45:
x in rngs
by A40, A42, A43, TARSKI:def 1;
consider yS being
set such that A46:
y in yS
and A47:
yS in Si
by A39, TARSKI:def 4;
consider j2 being
Element of
NAT such that A48:
yS = S . j2
and
j2 >= i
by A37, A47;
A49:
S . j2 = {(s . j2)}
by A10;
s . j2 in rngs
by A44, FUNCT_1:def 3;
then A50:
y in rngs
by A46, A48, A49, TARSKI:def 1;
(
x = y or
x <> y )
;
hence
dist (
x,
y)
<= 2
* (dist (a,b))
by A19, A27, A45, A50, METRIC_1:1;
verum end; then
SI is
bounded
by A19;
hence
R9 . i is
bounded
by A36, Th8;
verum end;
then reconsider R9 = R9 as non-empty pointwise_bounded SetSequence of (WellSpace (a,X)) by Def1;
take
R9
; ( R9 is closed & R9 is non-ascending & meet R9 is empty )
thus
( R9 is closed & R9 is non-ascending )
by A24, Th7; meet R9 is empty
for x, y being Point of (WellSpace (a,X)) st x <> y & x in rngs & y in rngs holds
dist (x,y) >= 2 * (dist (a,b))
by A27;
hence
meet R9 is empty
by A25, A19, A11, Lm7, FUNCT_2:19; verum