:: BORSUK_5 semantic presentation

theorem Th1: :: BORSUK_5:1
canceled;

theorem Th2: :: BORSUK_5:2
for b1, b2, b3 being set holds
not ( b1 c= b2 & b2 c= b1 \/ {b3} & not b1 \/ {b3} = b2 & not b1 = b2 )
proof
let c1, c2, c3 be set ;
assume E2: ( c1 c= c2 & c2 c= c1 \/ {c3} ) ;
assume ( c1 \/ {c3} <> c2 & c1 <> c2 ) ;
then E3: ( not c1 \/ {c3} c= c2 & not c2 c= c1 ) by E2, XBOOLE_0:def 10;
not c3 in c2
proof
assume c3 in c2 ;
then {c3} c= c2 by ZFMISC_1:37;
hence not verum by E2, E3, XBOOLE_1:8;
end;
hence not verum by E2, E3, SETWISEO:5;
end;

theorem Th3: :: BORSUK_5:3
for b1, b2, b3, b4, b5, b6 being set holds {b1,b2,b3,b4,b5,b6} = {b1,b3,b6} \/ {b2,b4,b5}
proof
let c1, c2, c3, c4, c5, c6 be set ;
thus {c1,c2,c3,c4,c5,c6} c= {c1,c3,c6} \/ {c2,c4,c5} :: according to XBOOLE_0:def 10
proof
let c7 be set ; :: according to TARSKI:def 3
assume c7 in {c1,c2,c3,c4,c5,c6} ;
then not ( not c7 = c1 & not c7 = c2 & not c7 = c3 & not c7 = c4 & not c7 = c5 & not c7 = c6 ) by ENUMSET1:def 4;
then ( c7 in {c1,c3,c6} or c7 in {c2,c4,c5} ) by ENUMSET1:def 1;
hence c7 in {c1,c3,c6} \/ {c2,c4,c5} by XBOOLE_0:def 2;
end;
let c7 be set ; :: according to TARSKI:def 3
assume c7 in {c1,c3,c6} \/ {c2,c4,c5} ;
then ( c7 in {c1,c3,c6} or c7 in {c2,c4,c5} ) by XBOOLE_0:def 2;
then not ( not c7 = c1 & not c7 = c3 & not c7 = c6 & not c7 = c2 & not c7 = c4 & not c7 = c5 ) by ENUMSET1:def 1;
hence c7 in {c1,c2,c3,c4,c5,c6} by ENUMSET1:def 4;
end;

definition
let c1, c2, c3, c4, c5, c6 be set ;
pred c1,c2,c3,c4,c5,c6 are_mutually_different means :Def1: :: BORSUK_5:def 1
( a1 <> a2 & a1 <> a3 & a1 <> a4 & a1 <> a5 & a1 <> a6 & a2 <> a3 & a2 <> a4 & a2 <> a5 & a2 <> a6 & a3 <> a4 & a3 <> a5 & a3 <> a6 & a4 <> a5 & a4 <> a6 & a5 <> a6 );
end;

:: deftheorem Def1 defines are_mutually_different BORSUK_5:def 1 :
for b1, b2, b3, b4, b5, b6 being set holds
( b1,b2,b3,b4,b5,b6 are_mutually_different iff ( b1 <> b2 & b1 <> b3 & b1 <> b4 & b1 <> b5 & b1 <> b6 & b2 <> b3 & b2 <> b4 & b2 <> b5 & b2 <> b6 & b3 <> b4 & b3 <> b5 & b3 <> b6 & b4 <> b5 & b4 <> b6 & b5 <> b6 ) );

definition
let c1, c2, c3, c4, c5, c6, c7 be set ;
pred c1,c2,c3,c4,c5,c6,c7 are_mutually_different means :Def2: :: BORSUK_5:def 2
( a1 <> a2 & a1 <> a3 & a1 <> a4 & a1 <> a5 & a1 <> a6 & a1 <> a7 & a2 <> a3 & a2 <> a4 & a2 <> a5 & a2 <> a6 & a2 <> a7 & a3 <> a4 & a3 <> a5 & a3 <> a6 & a3 <> a7 & a4 <> a5 & a4 <> a6 & a4 <> a7 & a5 <> a6 & a5 <> a7 & a6 <> a7 );
end;

:: deftheorem Def2 defines are_mutually_different BORSUK_5:def 2 :
for b1, b2, b3, b4, b5, b6, b7 being set holds
( b1,b2,b3,b4,b5,b6,b7 are_mutually_different iff ( b1 <> b2 & b1 <> b3 & b1 <> b4 & b1 <> b5 & b1 <> b6 & b1 <> b7 & b2 <> b3 & b2 <> b4 & b2 <> b5 & b2 <> b6 & b2 <> b7 & b3 <> b4 & b3 <> b5 & b3 <> b6 & b3 <> b7 & b4 <> b5 & b4 <> b6 & b4 <> b7 & b5 <> b6 & b5 <> b7 & b6 <> b7 ) );

theorem Th4: :: BORSUK_5:4
for b1, b2, b3, b4, b5, b6 being set holds
( b1,b2,b3,b4,b5,b6 are_mutually_different implies card {b1,b2,b3,b4,b5,b6} = 6 )
proof
let c1, c2, c3, c4, c5, c6 be set ;
assume c1,c2,c3,c4,c5,c6 are_mutually_different ;
then E5: ( c1 <> c2 & c1 <> c3 & c1 <> c4 & c1 <> c5 & c1 <> c6 & c2 <> c3 & c2 <> c4 & c2 <> c5 & c2 <> c6 & c3 <> c4 & c3 <> c5 & c3 <> c6 & c4 <> c5 & c4 <> c6 & c5 <> c6 ) by Def1;
then c1,c2,c3,c4,c5 are_mutually_different by CARD_2:def 4;
then E6: card {c1,c2,c3,c4,c5} = 5 by CARD_2:82;
( not c6 in {c1,c2,c3,c4,c5} & {c1,c2,c3,c4,c5} is finite & {c1,c2,c3,c4,c5,c6} = {c1,c2,c3,c4,c5} \/ {c6} ) by E5, ENUMSET1:def 3, ENUMSET1:55;
hence card {c1,c2,c3,c4,c5,c6} = 5 + 1 by E6, CARD_2:54
.= 6 ;

end;

theorem Th5: :: BORSUK_5:5
for b1, b2, b3, b4, b5, b6, b7 being set holds
( b1,b2,b3,b4,b5,b6,b7 are_mutually_different implies card {b1,b2,b3,b4,b5,b6,b7} = 7 )
proof
let c1, c2, c3, c4, c5, c6, c7 be set ;
assume c1,c2,c3,c4,c5,c6,c7 are_mutually_different ;
then E5: ( c1 <> c2 & c1 <> c3 & c1 <> c4 & c1 <> c5 & c1 <> c6 & c1 <> c7 & c2 <> c3 & c2 <> c4 & c2 <> c5 & c2 <> c6 & c2 <> c7 & c3 <> c4 & c3 <> c5 & c3 <> c6 & c3 <> c7 & c4 <> c5 & c4 <> c6 & c4 <> c7 & c5 <> c6 & c5 <> c7 & c6 <> c7 ) by Def2;
then c1,c2,c3,c4,c5,c6 are_mutually_different by Def1;
then E6: card {c1,c2,c3,c4,c5,c6} = 6 by Th4;
( not c7 in {c1,c2,c3,c4,c5,c6} & {c1,c2,c3,c4,c5,c6} is finite & {c1,c2,c3,c4,c5,c6,c7} = {c1,c2,c3,c4,c5,c6} \/ {c7} ) by E5, ENUMSET1:def 4, ENUMSET1:61;
hence card {c1,c2,c3,c4,c5,c6,c7} = 6 + 1 by E6, CARD_2:54
.= 7 ;

end;

theorem Th6: :: BORSUK_5:6
for b1, b2, b3, b4, b5, b6 being set holds
( {b1,b2,b3} misses {b4,b5,b6} implies ( b1 <> b4 & b1 <> b5 & b1 <> b6 & b2 <> b4 & b2 <> b5 & b2 <> b6 & b3 <> b4 & b3 <> b5 & b3 <> b6 ) )
proof
let c1, c2, c3, c4, c5, c6 be set ;
assume E6: {c1,c2,c3} misses {c4,c5,c6} ;
assume not ( not c1 = c4 & not c1 = c5 & not c1 = c6 & not c2 = c4 & not c2 = c5 & not c2 = c6 & not c3 = c4 & not c3 = c5 & not c3 = c6 ) ;
then E7: not ( not c4 in {c1,c2,c3} & not c5 in {c1,c2,c3} & not c6 in {c1,c2,c3} ) by ENUMSET1:def 1;
( c4 in {c4,c5,c6} & c5 in {c4,c5,c6} & c6 in {c4,c5,c6} ) by ENUMSET1:def 1;
hence not verum by E6, E7, XBOOLE_0:3;
end;

theorem Th7: :: BORSUK_5:7
for b1, b2, b3, b4, b5, b6 being set holds
( b1,b2,b3 are_mutually_different & b4,b5,b6 are_mutually_different & {b1,b2,b3} misses {b4,b5,b6} implies b1,b2,b3,b4,b5,b6 are_mutually_different )
proof
let c1, c2, c3, c4, c5, c6 be set ;
assume that
E6: c1,c2,c3 are_mutually_different and
E7: c4,c5,c6 are_mutually_different and
E8: {c1,c2,c3} misses {c4,c5,c6} ;
E9: ( c1 <> c2 & c2 <> c3 & c1 <> c3 ) by E6, INCPROJ:def 5;
E10: ( c4 <> c5 & c5 <> c6 & c4 <> c6 ) by E7, INCPROJ:def 5;
( c1 <> c4 & c1 <> c5 & c1 <> c6 & c2 <> c4 & c2 <> c5 & c2 <> c6 & c3 <> c4 & c3 <> c5 & c3 <> c6 ) by E8, Th6;
hence c1,c2,c3,c4,c5,c6 are_mutually_different by E9, E10, Def1;
end;

theorem Th8: :: BORSUK_5:8
for b1, b2, b3, b4, b5, b6, b7 being set holds
( b1,b2,b3,b4,b5,b6 are_mutually_different & {b1,b2,b3,b4,b5,b6} misses {b7} implies b1,b2,b3,b4,b5,b6,b7 are_mutually_different )
proof
let c1, c2, c3, c4, c5, c6, c7 be set ;
assume that
E6: c1,c2,c3,c4,c5,c6 are_mutually_different and
E7: {c1,c2,c3,c4,c5,c6} misses {c7} ;
E8: ( c1 <> c2 & c1 <> c3 & c1 <> c4 & c1 <> c5 & c1 <> c6 & c2 <> c3 & c2 <> c4 & c2 <> c5 & c2 <> c6 & c3 <> c4 & c3 <> c5 & c3 <> c6 & c4 <> c5 & c4 <> c6 & c5 <> c6 ) by E6, Def1;
not c7 in {c1,c2,c3,c4,c5,c6} by E7, ZFMISC_1:54;
then ( c7 <> c1 & c7 <> c2 & c7 <> c3 & c7 <> c4 & c7 <> c5 & c7 <> c6 ) by ENUMSET1:def 4;
hence c1,c2,c3,c4,c5,c6,c7 are_mutually_different by E8, Def2;
end;

theorem Th9: :: BORSUK_5:9
for b1, b2, b3, b4, b5, b6, b7 being set holds
( b1,b2,b3,b4,b5,b6,b7 are_mutually_different implies b7,b1,b2,b3,b4,b5,b6 are_mutually_different )
proof
let c1, c2, c3, c4, c5, c6, c7 be set ;
assume c1,c2,c3,c4,c5,c6,c7 are_mutually_different ;
then ( c1 <> c2 & c1 <> c3 & c1 <> c4 & c1 <> c5 & c1 <> c6 & c1 <> c7 & c2 <> c3 & c2 <> c4 & c2 <> c5 & c2 <> c6 & c2 <> c7 & c3 <> c4 & c3 <> c5 & c3 <> c6 & c3 <> c7 & c4 <> c5 & c4 <> c6 & c4 <> c7 & c5 <> c6 & c5 <> c7 & c6 <> c7 ) by Def2;
hence c7,c1,c2,c3,c4,c5,c6 are_mutually_different by Def2;
end;

theorem Th10: :: BORSUK_5:10
for b1, b2, b3, b4, b5, b6, b7 being set holds
( b1,b2,b3,b4,b5,b6,b7 are_mutually_different implies b1,b2,b5,b3,b6,b7,b4 are_mutually_different )
proof
let c1, c2, c3, c4, c5, c6, c7 be set ;
assume c1,c2,c3,c4,c5,c6,c7 are_mutually_different ;
then ( c1 <> c2 & c1 <> c3 & c1 <> c4 & c1 <> c5 & c1 <> c6 & c1 <> c7 & c2 <> c3 & c2 <> c4 & c2 <> c5 & c2 <> c6 & c2 <> c7 & c3 <> c4 & c3 <> c5 & c3 <> c6 & c3 <> c7 & c4 <> c5 & c4 <> c6 & c4 <> c7 & c5 <> c6 & c5 <> c7 & c6 <> c7 ) by Def2;
hence c1,c2,c5,c3,c6,c7,c4 are_mutually_different by Def2;
end;

theorem Th11: :: BORSUK_5:11
for b1 being non empty TopSpace
for b2, b3 being Point of b1 holds
not ( ex b4 being Function of I[01] ,b1 st
( b4 is continuous & b4 . 0 = b2 & b4 . 1 = b3 ) & ( for b4 being Function of I[01] ,b1 holds
not ( b4 is continuous & b4 . 0 = b3 & b4 . 1 = b2 ) ) ) by BORSUK_2:18;

Lemma7: R^1 is arcwise_connected
proof
let c1, c2 be Point of R^1 ; :: according to BORSUK_2:def 3
per cases ( c1 <= c2 or c2 <= c1 ) ;
suppose E8: c1 <= c2 ;
reconsider c3 = [.c1,c2.] as Subset of R^1 by TOPMETR:24;
reconsider c4 = c3 as non empty Subset of R^1 by E8, RCOMP_1:48;
E9: Closed-Interval-TSpace c1,c2 = R^1 | c4 by E8, TOPMETR:26;
then E10: L[01] ((#) c1,c2),(c1,c2 (#) ) is continuous Function of I[01] ,(R^1 | c4) by E8, TOPMETR:27, TREAL_1:11;
the carrier of (R^1 | c4) c= the carrier of R^1 by BORSUK_1:35;
then reconsider c5 = L[01] ((#) c1,c2),(c1,c2 (#) ) as Function of the carrier of I[01] ,the carrier of R^1 by E9, FUNCT_2:9, TOPMETR:27;
reconsider c6 = c5 as Function of I[01] ,R^1 ;
take c6 ; :: according to BORSUK_2:def 1
thus c6 is continuous by E10, TOPMETR:7;
0 = (#) 0,1 by TREAL_1:def 1;
hence c6 . 0 = (#) c1,c2 by E8, TREAL_1:12
.= c1 by E8, TREAL_1:def 1 ;

1 = 0,1 (#) by TREAL_1:def 2;
hence c6 . 1 = c1,c2 (#) by E8, TREAL_1:12
.= c2 by E8, TREAL_1:def 2 ;

end;
suppose E8: c2 <= c1 ;
reconsider c3 = [.c2,c1.] as Subset of R^1 by TOPMETR:24;
c2 in c3 by E8, RCOMP_1:48;
then reconsider c4 = [.c2,c1.] as non empty Subset of R^1 ;
E9: Closed-Interval-TSpace c2,c1 = R^1 | c4 by E8, TOPMETR:26;
then E10: L[01] ((#) c2,c1),(c2,c1 (#) ) is continuous Function of I[01] ,(R^1 | c4) by E8, TOPMETR:27, TREAL_1:11;
the carrier of (R^1 | c4) c= the carrier of R^1 by BORSUK_1:35;
then reconsider c5 = L[01] ((#) c2,c1),(c2,c1 (#) ) as Function of the carrier of I[01] ,the carrier of R^1 by E9, FUNCT_2:9, TOPMETR:27;
reconsider c6 = c5 as Function of I[01] ,R^1 ;
E11: c6 is continuous by E10, TOPMETR:7;
0 = (#) 0,1 by TREAL_1:def 1;
then E12: c6 . 0 = (#) c2,c1 by E8, TREAL_1:12
.= c2 by E8, TREAL_1:def 1 ;
1 = 0,1 (#) by TREAL_1:def 2;
then E13: c6 . 1 = c2,c1 (#) by E8, TREAL_1:12
.= c1 by E8, TREAL_1:def 2 ;
then c2,c1 are_connected by E11, E12, BORSUK_2:def 1;
then reconsider c7 = c6 as Path of c2,c1 by E11, E12, E13, BORSUK_2:def 2;
take c8 = - c7; :: according to BORSUK_2:def 1
ex b1 being Function of I[01] ,R^1 st
( b1 is continuous & b1 . 0 = c1 & b1 . 1 = c2 ) by E11, E12, E13, Th11;
then c1,c2 are_connected by BORSUK_2:def 1;
hence ( c8 is continuous & c8 . 0 = c1 & c8 . 1 = c2 ) by BORSUK_2:def 2;
end;
end;
end;

registration
cluster R^1 -> arcwise_connected ;
coherence
R^1 is arcwise_connected
by Lemma7;
end;

registration
cluster non empty connected TopStruct ;
existence
ex b1 being TopSpace st
( b1 is connected & not b1 is empty )
proof
take R^1 ;
thus ( R^1 is connected & not R^1 is empty ) ;
end;
end;

theorem Th12: :: BORSUK_5:12
canceled;

theorem Th13: :: BORSUK_5:13
[#] R^1 = REAL by TOPMETR:24;

notation
let c1 be real number ;
synonym ].-infty,c1.] for left_closed_halfline c1;
synonym ].-infty,c1.[ for left_open_halfline c1;
synonym [.c1,+infty.[ for right_closed_halfline c1;
synonym ].c1,+infty.[ for right_open_halfline c1;
end;

theorem Th14: :: BORSUK_5:14
for b1, b2 being real number holds
( b1 in ].b2,+infty.[ iff b1 > b2 )
proof
let c1, c2 be real number ;
E10: c1 is Element of REAL by XREAL_0:def 1;
hereby
assume c1 in ].c2,+infty.[ ;
then c1 in { b1 where B is Element of REAL : c2 < b1 } by LIMFUNC1:def 3;
then consider c3 being Element of REAL such that
E11: ( c3 = c1 & c2 < c3 ) ;
thus c2 < c1 by E11;
end;
assume c2 < c1 ;
then c1 in { b1 where B is Element of REAL : c2 < b1 } by E10;
hence c1 in ].c2,+infty.[ by LIMFUNC1:def 3;
end;

theorem Th15: :: BORSUK_5:15
for b1, b2 being real number holds
( b1 in [.b2,+infty.[ iff b1 >= b2 )
proof
let c1, c2 be real number ;
E11: c1 is Element of REAL by XREAL_0:def 1;
hereby
assume c1 in [.c2,+infty.[ ;
then c1 in { b1 where B is Element of REAL : c2 <= b1 } by LIMFUNC1:def 2;
then consider c3 being Element of REAL such that
E12: ( c3 = c1 & c2 <= c3 ) ;
thus c2 <= c1 by E12;
end;
assume c2 <= c1 ;
then c1 in { b1 where B is Element of REAL : c2 <= b1 } by E11;
hence c1 in [.c2,+infty.[ by LIMFUNC1:def 2;
end;

theorem Th16: :: BORSUK_5:16
for b1, b2 being real number holds
( b1 in ].-infty,b2.] iff b1 <= b2 )
proof
let c1, c2 be real number ;
E12: c1 is Element of REAL by XREAL_0:def 1;
hereby
assume c1 in ].-infty,c2.] ;
then c1 in { b1 where B is Element of REAL : b1 <= c2 } by LIMFUNC1:def 1;
then consider c3 being Element of REAL such that
E13: ( c3 = c1 & c2 >= c3 ) ;
thus c2 >= c1 by E13;
end;
assume c2 >= c1 ;
then c1 in { b1 where B is Element of REAL : c2 >= b1 } by E12;
hence c1 in ].-infty,c2.] by LIMFUNC1:def 1;
end;

theorem Th17: :: BORSUK_5:17
for b1, b2 being real number holds
( b1 in ].-infty,b2.[ iff b1 < b2 )
proof
let c1, c2 be real number ;
E13: c1 is Element of REAL by XREAL_0:def 1;
hereby
assume c1 in ].-infty,c2.[ ;
then c1 in { b1 where B is Element of REAL : b1 < c2 } by PROB_1:def 15;
then consider c3 being Element of REAL such that
E14: ( c3 = c1 & c2 > c3 ) ;
thus c2 > c1 by E14;
end;
assume c1 < c2 ;
then c1 in { b1 where B is Element of REAL : c2 > b1 } by E13;
hence c1 in ].-infty,c2.[ by PROB_1:def 15;
end;

theorem Th18: :: BORSUK_5:18
for b1 being real number holds REAL \ {b1} = ].-infty,b1.[ \/ ].b1,+infty.[
proof
let c1 be real number ;
[.c1,c1.] = {c1} by RCOMP_1:14;
hence REAL \ {c1} = ].-infty,c1.[ \/ ].c1,+infty.[ by LIMFUNC1:25;
end;

theorem Th19: :: BORSUK_5:19
for b1, b2, b3, b4 being real number holds
( b1 < b2 & b2 <= b3 implies [.b1,b2.] misses ].b3,b4.] )
proof
let c1, c2, c3, c4 be real number ;
assume E15: ( c1 < c2 & c2 <= c3 ) ;
assume [.c1,c2.] meets ].c3,c4.] ;
then consider c5 being set such that
E16: ( c5 in [.c1,c2.] & c5 in ].c3,c4.] ) by XBOOLE_0:3;
reconsider c6 = c5 as real number by E16, XREAL_0:def 1;
( c6 <= c2 & c6 > c3 ) by E16, RCOMP_2:4, RCOMP_1:48;
hence not verum by E15, XXREAL_0:2;
end;

theorem Th20: :: BORSUK_5:20
for b1, b2, b3, b4 being real number holds
( b1 < b2 & b2 <= b3 implies [.b1,b2.[ misses [.b3,b4.] )
proof
let c1, c2, c3, c4 be real number ;
assume E16: ( c1 < c2 & c2 <= c3 ) ;
assume [.c1,c2.[ meets [.c3,c4.] ;
then consider c5 being set such that
E17: ( c5 in [.c1,c2.[ & c5 in [.c3,c4.] ) by XBOOLE_0:3;
reconsider c6 = c5 as real number by E17, XREAL_0:def 1;
( c6 < c2 & c6 >= c3 ) by E17, RCOMP_2:3, RCOMP_1:48;
hence not verum by E16, XXREAL_0:2;
end;

theorem Th21: :: BORSUK_5:21
for b1, b2 being Subset of R^1
for b3, b4, b5, b6 being real number holds
( b3 < b4 & b4 <= b5 & b5 < b6 & b1 = [.b3,b4.[ & b2 = ].b5,b6.] implies b1,b2 are_separated )
proof
let c1, c2 be Subset of R^1 ;
let c3, c4, c5, c6 be real number ;
assume that
E16: ( c3 < c4 & c4 <= c5 & c5 < c6 ) and
E17: c1 = [.c3,c4.[ and
E18: c2 = ].c5,c6.] ;
Cl [.c3,c4.[ = [.c3,c4.] by E16, BORSUK_4:21;
then Cl c1 = [.c3,c4.] by E17, TOPREAL6:80;
then E19: Cl c1 misses c2 by E16, E18, Th19;
Cl ].c5,c6.] = [.c5,c6.] by E16, BORSUK_4:20;
then Cl c2 = [.c5,c6.] by E18, TOPREAL6:80;
then Cl c2 misses c1 by E16, E17, Th20;
hence c1,c2 are_separated by E19, CONNSP_1:def 1;
end;

Lemma16: for b1 being real number holds REAL \ ].-infty,b1.[ = [.b1,+infty.[
by LIMFUNC1:24;

Lemma17: for b1 being real number holds REAL \ ].-infty,b1.] = ].b1,+infty.[
by LIMFUNC1:24;

Lemma18: for b1 being real number holds REAL \ [.b1,+infty.[ = ].-infty,b1.[
by LIMFUNC1:24;

theorem Th22: :: BORSUK_5:22
canceled;

theorem Th23: :: BORSUK_5:23
canceled;

theorem Th24: :: BORSUK_5:24
canceled;

theorem Th25: :: BORSUK_5:25
canceled;

theorem Th26: :: BORSUK_5:26
for b1 being real number holds ].-infty,b1.] misses ].b1,+infty.[
proof
let c1 be real number ;
REAL \ ].-infty,c1.] = ].c1,+infty.[ by Lemma17;
hence ].-infty,c1.] misses ].c1,+infty.[ by XBOOLE_1:79;
end;

theorem Th27: :: BORSUK_5:27
for b1 being real number holds ].-infty,b1.[ misses [.b1,+infty.[
proof
let c1 be real number ;
REAL \ ].-infty,c1.[ = [.c1,+infty.[ by Lemma16;
hence ].-infty,c1.[ misses [.c1,+infty.[ by XBOOLE_1:79;
end;

theorem Th28: :: BORSUK_5:28
for b1, b2, b3 being real number holds
( b1 <= b3 & b3 <= b2 implies [.b1,b2.] \/ [.b3,+infty.[ = [.b1,+infty.[ )
proof
let c1, c2, c3 be real number ;
assume E22: ( c1 <= c3 & c3 <= c2 ) ;
E23: [.c1,+infty.[ c= [.c1,c2.] \/ [.c3,+infty.[
proof
let c4 be set ; :: according to TARSKI:def 3
assume E24: c4 in [.c1,+infty.[ ;
then reconsider c5 = c4 as Real ;
E25: c1 <= c5 by E24, Th15;
per cases not ( not c5 <= c2 & c5 <= c2 ) ;
suppose c5 <= c2 ;
then c5 in [.c1,c2.] by E25, RCOMP_1:48;
hence c4 in [.c1,c2.] \/ [.c3,+infty.[ by XBOOLE_0:def 2;
end;
suppose not c5 <= c2 ;
then c3 <= c5 by E22, XXREAL_0:2;
then c5 in [.c3,+infty.[ by Th15;
hence c4 in [.c1,c2.] \/ [.c3,+infty.[ by XBOOLE_0:def 2;
end;
end;
end;
[.c1,c2.] \/ [.c3,+infty.[ c= [.c1,+infty.[
proof end;
hence [.c1,c2.] \/ [.c3,+infty.[ = [.c1,+infty.[ by E23, XBOOLE_0:def 10;
end;

theorem Th29: :: BORSUK_5:29
for b1, b2, b3 being real number holds
( b1 <= b3 & b3 <= b2 implies ].-infty,b3.] \/ [.b1,b2.] = ].-infty,b2.] )
proof
let c1, c2, c3 be real number ;
assume E23: ( c1 <= c3 & c3 <= c2 ) ;
thus ].-infty,c3.] \/ [.c1,c2.] c= ].-infty,c2.] :: according to XBOOLE_0:def 10
proof
let c4 be set ; :: according to TARSKI:def 3
assume E24: c4 in ].-infty,c3.] \/ [.c1,c2.] ;
then reconsider c5 = c4 as real number by XREAL_0:def 1;
per cases ( c5 in ].-infty,c3.] or c5 in [.c1,c2.] ) by E24, XBOOLE_0:def 2;
suppose c5 in ].-infty,c3.] ;
then c5 <= c3 by Th16;
then c5 <= c2 by E23, XXREAL_0:2;
hence c4 in ].-infty,c2.] by Th16;
end;
suppose c5 in [.c1,c2.] ;
then c5 <= c2 by RCOMP_1:48;
hence c4 in ].-infty,c2.] by Th16;
end;
end;
end;
let c4 be set ; :: according to TARSKI:def 3
assume E24: c4 in ].-infty,c2.] ;
then reconsider c5 = c4 as real number by XREAL_0:def 1;
per cases not ( not c5 <= c3 & not c5 > c3 ) ;
suppose c5 <= c3 ;
then c5 in ].-infty,c3.] by Th16;
hence c4 in ].-infty,c3.] \/ [.c1,c2.] by XBOOLE_0:def 2;
end;
suppose c5 > c3 ;
then E25: c5 > c1 by E23, XXREAL_0:2;
c5 <= c2 by E24, Th16;
then c5 in [.c1,c2.] by E25, RCOMP_1:48;
hence c4 in ].-infty,c3.] \/ [.c1,c2.] by XBOOLE_0:def 2;
end;
end;
end;

registration
cluster -> real Element of RAT ;
coherence
for b1 being Element of RAT holds b1 is real
;
end;

registration
cluster -> real Element of the carrier of RealSpace ;
coherence
for b1 being Element of RealSpace holds b1 is real
by METRIC_1:def 14, XREAL_0:def 1;
end;

theorem Th30: :: BORSUK_5:30
canceled;

theorem Th31: :: BORSUK_5:31
canceled;

theorem Th32: :: BORSUK_5:32
canceled;

theorem Th33: :: BORSUK_5:33
for b1 being Subset of R^1
for b2 being Point of RealSpace holds
( b2 in Cl b1 iff for b3 being real number holds
not ( b3 > 0 & not Ball b2,b3 meets b1 ) ) by GOBOARD6:95, TOPMETR:def 7;

theorem Th34: :: BORSUK_5:34
for b1, b2 being Element of RealSpace holds
( b2 >= b1 implies dist b1,b2 = b2 - b1 )
proof
let c1, c2 be Element of RealSpace ;
assume c1 <= c2 ;
then E24: c2 - c1 >= 0 by XREAL_1:50;
dist c1,c2 = abs (c2 - c1) by TOPMETR:15
.= c2 - c1 by E24, ABSVALUE:def 1 ;
hence dist c1,c2 = c2 - c1 ;
end;

theorem Th35: :: BORSUK_5:35
for b1 being Subset of R^1 holds
( b1 = RAT implies Cl b1 = the carrier of R^1 )
proof
let c1 be Subset of R^1 ;
assume E25: c1 = RAT ;
Cl c1 = the carrier of R^1
proof
thus Cl c1 c= the carrier of R^1 ; :: according to XBOOLE_0:def 10
thus the carrier of R^1 c= Cl c1
proof
let c2 be set ; :: according to TARSKI:def 3
assume c2 in the carrier of R^1 ;
then reconsider c3 = c2 as Element of RealSpace by METRIC_1:def 14, TOPMETR:24;
now
let c4 be real number ;
assume E26: c4 > 0 ;
reconsider c5 = c3 + c4 as Element of RealSpace by METRIC_1:def 14, XREAL_0:def 1;
c3 < c5 by E26, XREAL_1:31;
then consider c6 being rational number such that
E27: ( c3 < c6 & c6 < c5 ) by RAT_1:22;
E28: c6 in c1 by E25, RAT_1:def 2;
reconsider c7 = c6 as Element of RealSpace by METRIC_1:def 14, XREAL_0:def 1;
c7 - c3 < c5 - c3 by E27, XREAL_1:11;
then dist c3,c7 < c4 by E27, Th34;
then c7 in Ball c3,c4 by METRIC_1:12;
hence Ball c3,c4 meets c1 by E28, XBOOLE_0:3;
end;
hence c2 in Cl c1 by GOBOARD6:95, TOPMETR:def 7;
end;
end;
hence Cl c1 = the carrier of R^1 ;
end;

theorem Th36: :: BORSUK_5:36
for b1 being Subset of R^1
for b2, b3 being real