let X be Subset-Family of REAL ; :: thesis: ( card X in continuum implies ex x being real number ex q being rational number st
( x < q & not [.x,q.[ in UniCl X ) )
assume A1:
card X in continuum
; :: thesis: ex x being real number ex q being rational number st
( x < q & not [.x,q.[ in UniCl X )
set Z = { x where x is Element of REAL : ex U being set st
( U in UniCl X & x is_local_minimum_of U ) } ;
consider z being Element of REAL \ { x where x is Element of REAL : ex U being set st
( U in UniCl X & x is_local_minimum_of U ) } ;
card { x where x is Element of REAL : ex U being set st
( U in UniCl X & x is_local_minimum_of U ) } in continuum
by A1, Th31;
then A2:
REAL \ { x where x is Element of REAL : ex U being set st
( U in UniCl X & x is_local_minimum_of U ) } <> {}
by CARD_2:4;
then A3:
( z in REAL & not z in { x where x is Element of REAL : ex U being set st
( U in UniCl X & x is_local_minimum_of U ) } )
by XBOOLE_0:def 5;
reconsider z = z as Element of REAL by A2, XBOOLE_0:def 5;
z + 0 < z + 1
by XREAL_1:8;
then consider q being rational number such that
A4:
( z < q & q < z + 1 )
by RAT_1:22;
take
z
; :: thesis: ex q being rational number st
( z < q & not [.z,q.[ in UniCl X )
take
q
; :: thesis: ( z < q & not [.z,q.[ in UniCl X )
thus
z < q
by A4; :: thesis: not [.z,q.[ in UniCl X
z is_local_minimum_of [.z,q.[
proof
thus
z in [.z,q.[
by A4, XXREAL_1:3;
:: according to TOPGEN_3:def 3 :: thesis: ex y being real number st
( y < z & ].y,z.[ misses [.z,q.[ )
take y =
z - 1;
:: thesis: ( y < z & ].y,z.[ misses [.z,q.[ )
z - 0 = z
;
hence
y < z
by XREAL_1:17;
:: thesis: ].y,z.[ misses [.z,q.[
assume
].y,z.[ meets [.z,q.[
;
:: thesis: contradiction
then consider a being
set such that A5:
(
a in ].y,z.[ &
a in [.z,q.[ )
by XBOOLE_0:3;
reconsider a =
a as
Element of
REAL by A5;
(
a < z &
z <= a )
by A5, XXREAL_1:3, XXREAL_1:4;
hence
contradiction
;
:: thesis: verum
end;
hence
not [.z,q.[ in UniCl X
by A3; :: thesis: verum