let C be non empty compact Subset of I[01]; ( C c= ].0,1.[ implies ex D being non empty closed_interval Subset of REAL st
( C c= D & D c= ].0,1.[ & lower_bound C = lower_bound D & upper_bound C = upper_bound D ) )
assume A1:
C c= ].0,1.[
; ex D being non empty closed_interval Subset of REAL st
( C c= D & D c= ].0,1.[ & lower_bound C = lower_bound D & upper_bound C = upper_bound D )
reconsider C9 = C as Subset of REAL by BORSUK_1:40, XBOOLE_1:1;
reconsider D = [.(lower_bound C9),(upper_bound C9).] as Subset of REAL ;
A2:
( C9 is bounded_below & C9 is bounded_above )
by Th22;
then A3:
lower_bound C9 <= upper_bound C9
by SEQ_4:11;
A4:
C c= D
A7:
C9 is closed
by Th24;
then A8:
lower_bound C9 in C9
by Th22, RCOMP_1:13;
A9:
upper_bound C9 in C9
by A7, Th22, RCOMP_1:12;
then A10:
D is non empty connected compact Subset of I[01]
by A2, A8, Th21, SEQ_4:11;
then A11:
D is non empty closed_interval Subset of REAL
by Th27;
then A12:
D = [.(lower_bound D),(upper_bound D).]
by INTEGRA1:4;
then A13:
upper_bound C9 = upper_bound D
by A3, XXREAL_1:66;
A14:
not 1 in D
A15:
lower_bound C9 = lower_bound D
by A3, A12, XXREAL_1:66;
A16:
not 0 in D
A17:
D c= ].0,1.[
by A10, A16, A14, BORSUK_1:40, XXREAL_1:5;
reconsider D = D as non empty closed_interval Subset of REAL by A3, MEASURE5:14;
take
D
; ( C c= D & D c= ].0,1.[ & lower_bound C = lower_bound D & upper_bound C = upper_bound D )
thus
( C c= D & D c= ].0,1.[ & lower_bound C = lower_bound D & upper_bound C = upper_bound D )
by A4, A3, A12, A17, XXREAL_1:66; verum