let G1 be _Graph; for v being object
for V being Subset of (the_Vertices_of G1)
for G2 being addAdjVertexAll of G1,v,V
for G3 being GraphComplement of G1 st not v in the_Vertices_of G1 & the_Edges_of G2 misses the_Edges_of G3 holds
ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2
let v be object ; for V being Subset of (the_Vertices_of G1)
for G2 being addAdjVertexAll of G1,v,V
for G3 being GraphComplement of G1 st not v in the_Vertices_of G1 & the_Edges_of G2 misses the_Edges_of G3 holds
ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2
let V be Subset of (the_Vertices_of G1); for G2 being addAdjVertexAll of G1,v,V
for G3 being GraphComplement of G1 st not v in the_Vertices_of G1 & the_Edges_of G2 misses the_Edges_of G3 holds
ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2
let G2 be addAdjVertexAll of G1,v,V; for G3 being GraphComplement of G1 st not v in the_Vertices_of G1 & the_Edges_of G2 misses the_Edges_of G3 holds
ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2
let G3 be GraphComplement of G1; ( not v in the_Vertices_of G1 & the_Edges_of G2 misses the_Edges_of G3 implies ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2 )
assume A1:
( not v in the_Vertices_of G1 & the_Edges_of G2 misses the_Edges_of G3 )
; ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2
consider E0 being set such that
( card V = card E0 & E0 misses the_Edges_of G1 )
and
the_Edges_of G2 = (the_Edges_of G1) \/ E0
and
A2:
for v1 being object st v1 in V holds
ex e1 being object st
( e1 in E0 & e1 Joins v1,v,G2 & ( for e2 being object st e2 Joins v1,v,G2 holds
e1 = e2 ) )
by A1, GLIB_007:def 4;
per cases
( (the_Vertices_of G1) \ V <> {} or (the_Vertices_of G1) \ V = {} )
;
suppose A3:
(the_Vertices_of G1) \ V <> {}
;
ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2set E =
{ [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ;
deffunc H1(
object )
-> object = $1
`2 ;
consider h being
Function such that A4:
(
dom h = { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } & ( for
x being
object st
x in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } holds
h . x = H1(
x) ) )
from FUNCT_1:sch 3();
set s =
(the_Source_of G3) +* h;
A5:
dom ((the_Source_of G3) +* h) =
(dom (the_Source_of G3)) \/ (dom h)
by FUNCT_4:def 1
.=
(the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A4, FUNCT_2:def 1
;
now for y being object holds
( ( y in (the_Vertices_of G1) \ V implies y in rng h ) & ( y in rng h implies y in (the_Vertices_of G1) \ V ) )let y be
object ;
( ( y in (the_Vertices_of G1) \ V implies y in rng h ) & ( y in rng h implies y in (the_Vertices_of G1) \ V ) )hereby ( y in rng h implies y in (the_Vertices_of G1) \ V )
set x =
[{(the_Edges_of G2),(the_Edges_of G3)},y];
assume
y in (the_Vertices_of G1) \ V
;
y in rng hthen A6:
[{(the_Edges_of G2),(the_Edges_of G3)},y] in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
;
then h . [{(the_Edges_of G2),(the_Edges_of G3)},y] =
[{(the_Edges_of G2),(the_Edges_of G3)},y] `2
by A4
.=
y
;
hence
y in rng h
by A4, A6, FUNCT_1:def 3;
verum
end; assume
y in rng h
;
y in (the_Vertices_of G1) \ Vthen consider x being
object such that A7:
(
x in dom h &
h . x = y )
by FUNCT_1:def 3;
reconsider x =
x as
set by TARSKI:1;
consider w being
Element of
(the_Vertices_of G1) \ V such that A8:
x = [{(the_Edges_of G2),(the_Edges_of G3)},w]
by A4, A7;
h . x =
x `2
by A4, A7
.=
w
by A8
;
hence
y in (the_Vertices_of G1) \ V
by A3, A7;
verum end; then A9:
rng h =
(the_Vertices_of G1) \ V
by TARSKI:2
.=
(the_Vertices_of G3) \ V
by Th98
;
then A10:
(rng (the_Source_of G3)) \/ (rng h) c= the_Vertices_of G3
by XBOOLE_1:8;
rng ((the_Source_of G3) +* h) c= (rng (the_Source_of G3)) \/ (rng h)
by FUNCT_4:17;
then A11:
rng ((the_Source_of G3) +* h) c= the_Vertices_of G3
by A10, XBOOLE_1:1;
the_Vertices_of G3 c= (the_Vertices_of G3) \/ {v}
by XBOOLE_1:7;
then reconsider s =
(the_Source_of G3) +* h as
Function of
((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),
((the_Vertices_of G3) \/ {v}) by A5, A11, XBOOLE_1:1, FUNCT_2:2;
set t =
(the_Target_of G3) +* ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v);
A12:
dom ((the_Target_of G3) +* ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v)) =
(dom (the_Target_of G3)) \/ (dom ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v))
by FUNCT_4:def 1
.=
(the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by FUNCT_2:def 1
;
the_Vertices_of G3 c= (the_Vertices_of G3) \/ {v}
by XBOOLE_1:7;
then A13:
rng (the_Target_of G3) c= (the_Vertices_of G3) \/ {v}
by XBOOLE_1:1;
A14:
{v} c= (the_Vertices_of G3) \/ {v}
by XBOOLE_1:7;
A15:
rng ((the_Target_of G3) +* ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v)) c= (rng (the_Target_of G3)) \/ (rng ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v))
by FUNCT_4:17;
rng ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v) c= (the_Vertices_of G3) \/ {v}
by A14, XBOOLE_1:1;
then
(rng (the_Target_of G3)) \/ (rng ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v)) c= (the_Vertices_of G3) \/ {v}
by A13, XBOOLE_1:8;
then reconsider t =
(the_Target_of G3) +* ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v) as
Function of
((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),
((the_Vertices_of G3) \/ {v}) by A12, A15, XBOOLE_1:1, FUNCT_2:2;
A16:
{ [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } misses the_Edges_of G3
proof
assume
{ [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } meets the_Edges_of G3
;
contradiction
then consider e being
object such that A17:
(
e in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } &
e in the_Edges_of G3 )
by XBOOLE_0:3;
reconsider e =
e as
set by TARSKI:1;
consider w being
Element of
(the_Vertices_of G1) \ V such that A18:
e = [{(the_Edges_of G2),(the_Edges_of G3)},w]
by A17;
A19:
the_Edges_of G3 in {(the_Edges_of G2),(the_Edges_of G3)}
by TARSKI:def 2;
A20:
{(the_Edges_of G2),(the_Edges_of G3)} in {{(the_Edges_of G2),(the_Edges_of G3)}}
by TARSKI:def 1;
e = {{{(the_Edges_of G2),(the_Edges_of G3)},w},{{(the_Edges_of G2),(the_Edges_of G3)}}}
by A18, TARSKI:def 5;
then
{{(the_Edges_of G2),(the_Edges_of G3)}} in e
by TARSKI:def 2;
hence
contradiction
by A17, A19, A20, XREGULAR:8;
verum
end; A21:
{ [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } misses the_Edges_of G2
proof
assume
{ [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } meets the_Edges_of G2
;
contradiction
then consider e being
object such that A22:
(
e in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } &
e in the_Edges_of G2 )
by XBOOLE_0:3;
reconsider e =
e as
set by TARSKI:1;
consider w being
Element of
(the_Vertices_of G1) \ V such that A23:
e = [{(the_Edges_of G2),(the_Edges_of G3)},w]
by A22;
A24:
the_Edges_of G2 in {(the_Edges_of G2),(the_Edges_of G3)}
by TARSKI:def 2;
A25:
{(the_Edges_of G2),(the_Edges_of G3)} in {{(the_Edges_of G2),(the_Edges_of G3)}}
by TARSKI:def 1;
e = {{{(the_Edges_of G2),(the_Edges_of G3)},w},{{(the_Edges_of G2),(the_Edges_of G3)}}}
by A23, TARSKI:def 5;
then
{{(the_Edges_of G2),(the_Edges_of G3)}} in e
by TARSKI:def 2;
hence
contradiction
by A22, A24, A25, XREGULAR:8;
verum
end; set G4 =
createGraph (
((the_Vertices_of G3) \/ {v}),
((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),
s,
t);
now ( the_Vertices_of G3 c= the_Vertices_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t)) & the_Edges_of G3 c= the_Edges_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t)) & ( for e being set st e in the_Edges_of G3 holds
( (the_Source_of G3) . e = (the_Source_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e & (the_Target_of G3) . e = (the_Target_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e ) ) )thus
the_Vertices_of G3 c= the_Vertices_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))
by XBOOLE_1:7;
( the_Edges_of G3 c= the_Edges_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t)) & ( for e being set st e in the_Edges_of G3 holds
( (the_Source_of G3) . e = (the_Source_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e & (the_Target_of G3) . e = (the_Target_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e ) ) )thus
the_Edges_of G3 c= the_Edges_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))
by XBOOLE_1:7;
for e being set st e in the_Edges_of G3 holds
( (the_Source_of G3) . e = (the_Source_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e & (the_Target_of G3) . e = (the_Target_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e )let e be
set ;
( e in the_Edges_of G3 implies ( (the_Source_of G3) . e = (the_Source_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e & (the_Target_of G3) . e = (the_Target_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e ) )assume A26:
e in the_Edges_of G3
;
( (the_Source_of G3) . e = (the_Source_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e & (the_Target_of G3) . e = (the_Target_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e )then
e in (the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by XBOOLE_0:def 3;
then A27:
not
e in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A16, A26, XBOOLE_0:5;
then A28:
not
e in dom ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v)
;
thus (the_Source_of G3) . e =
s . e
by A4, A27, FUNCT_4:11
.=
(the_Source_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e
;
(the_Target_of G3) . e = (the_Target_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . ethus (the_Target_of G3) . e =
t . e
by A28, FUNCT_4:11
.=
(the_Target_of (createGraph (((the_Vertices_of G3) \/ {v}),((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),s,t))) . e
;
verum end; then reconsider G4 =
createGraph (
((the_Vertices_of G3) \/ {v}),
((the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ),
s,
t) as
Supergraph of
G3 by GLIB_006:def 9;
(the_Vertices_of G1) \ V c= the_Vertices_of G1
;
then A29:
(
(the_Vertices_of G1) \ V c= the_Vertices_of G3 & not
v in the_Vertices_of G3 )
by A1, Th98;
now ( the_Vertices_of G4 = (the_Vertices_of G3) \/ {v} & ( for e being object holds
( not e Joins v,v,G4 & ( for v1 being object holds
( ( not v1 in (the_Vertices_of G1) \ V implies not e Joins v1,v,G4 ) & ( for v2 being object st v1 <> v & v2 <> v & e DJoins v1,v2,G4 holds
e DJoins v1,v2,G3 ) ) ) ) ) & ex E being set st
( card ((the_Vertices_of G1) \ V) = card E & E misses the_Edges_of G3 & the_Edges_of G4 = (the_Edges_of G3) \/ E & ( for v1 being object st v1 in (the_Vertices_of G1) \ V holds
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) ) ) ) )thus
the_Vertices_of G4 = (the_Vertices_of G3) \/ {v}
;
( ( for e being object holds
( not e Joins v,v,G4 & ( for v1 being object holds
( ( not v1 in (the_Vertices_of G1) \ V implies not e Joins v1,v,G4 ) & ( for v2 being object st v1 <> v & v2 <> v & e DJoins v1,v2,G4 holds
e DJoins v1,v2,G3 ) ) ) ) ) & ex E being set st
( card ((the_Vertices_of G1) \ V) = card E & E misses the_Edges_of G3 & the_Edges_of G4 = (the_Edges_of G3) \/ E & ( for v1 being object st v1 in (the_Vertices_of G1) \ V holds
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) ) ) ) )hereby ex E being set st
( card ((the_Vertices_of G1) \ V) = card E & E misses the_Edges_of G3 & the_Edges_of G4 = (the_Edges_of G3) \/ E & ( for v1 being object st v1 in (the_Vertices_of G1) \ V holds
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) ) ) )
let e be
object ;
( not e Joins v,v,G4 & ( for v1 being object holds
( ( not v1 in (the_Vertices_of G1) \ V implies not e Joins v1,v,G4 ) & ( for v2 being object st v1 <> v & v2 <> v & e DJoins v1,v2,G4 holds
e DJoins v1,v2,G3 ) ) ) )thus
not
e Joins v,
v,
G4
for v1 being object holds
( ( not v1 in (the_Vertices_of G1) \ V implies not e Joins v1,v,G4 ) & ( for v2 being object st v1 <> v & v2 <> v & e DJoins v1,v2,G4 holds
e DJoins v1,v2,G3 ) )proof
assume A30:
e Joins v,
v,
G4
;
contradiction
per cases then
( e Joins v,v,G3 or not e in the_Edges_of G3 )
by GLIB_006:72;
suppose A31:
not
e in the_Edges_of G3
;
contradiction
e in the_Edges_of G4
by A30, GLIB_000:def 13;
then
e in (the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
;
then A32:
e in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A16, A31, XBOOLE_0:5;
then consider w being
Element of
(the_Vertices_of G1) \ V such that A33:
e = [{(the_Edges_of G2),(the_Edges_of G3)},w]
;
(the_Source_of G4) . e =
s . e
.=
h . e
by A4, A32, FUNCT_4:13
.=
[{(the_Edges_of G2),(the_Edges_of G3)},w] `2
by A4, A32, A33
.=
w
;
then
v = w
by A30, GLIB_000:def 13;
then
v in (the_Vertices_of G1) \ V
by A3;
hence
contradiction
by A1;
verum end; end;
end; let v1 be
object ;
( ( not v1 in (the_Vertices_of G1) \ V implies not e Joins v1,v,G4 ) & ( for v2 being object st v1 <> v & v2 <> v & e DJoins v1,v2,G4 holds
e DJoins v1,v2,G3 ) )hereby for v2 being object st v1 <> v & v2 <> v & e DJoins v1,v2,G4 holds
e DJoins v1,v2,G3
assume A34:
not
v1 in (the_Vertices_of G1) \ V
;
not e Joins v1,v,G4assume A35:
e Joins v1,
v,
G4
;
contradictionper cases then
( e Joins v1,v,G3 or not e in the_Edges_of G3 )
by GLIB_006:72;
suppose A36:
not
e in the_Edges_of G3
;
contradiction
e in the_Edges_of G4
by A35, GLIB_000:def 13;
then
e in (the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
;
then A37:
e in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A36, XBOOLE_0:def 3;
then consider w being
Element of
(the_Vertices_of G1) \ V such that A38:
e = [{(the_Edges_of G2),(the_Edges_of G3)},w]
;
(the_Source_of G4) . e =
s . e
.=
h . e
by A4, A37, FUNCT_4:13
.=
[{(the_Edges_of G2),(the_Edges_of G3)},w] `2
by A4, A37, A38
.=
w
;
end; end;
end; let v2 be
object ;
( v1 <> v & v2 <> v & e DJoins v1,v2,G4 implies e DJoins v1,v2,G3 )assume A39:
(
v1 <> v &
v2 <> v &
e DJoins v1,
v2,
G4 )
;
e DJoins v1,v2,G3
e in the_Edges_of G3
proof
assume A40:
not
e in the_Edges_of G3
;
contradiction
e in the_Edges_of G4
by A39, GLIB_000:def 14;
then
e in (the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
;
then A41:
e in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A40, XBOOLE_0:def 3;
then A42:
e in dom ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v)
;
(the_Target_of G4) . e =
t . e
.=
( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v) . e
by A42, FUNCT_4:13
.=
v
by A41, FUNCOP_1:7
;
hence
contradiction
by A39, GLIB_000:def 14;
verum
end; hence
e DJoins v1,
v2,
G3
by A39, GLIB_006:71;
verum
end; take E =
{ [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } ;
( card ((the_Vertices_of G1) \ V) = card E & E misses the_Edges_of G3 & the_Edges_of G4 = (the_Edges_of G3) \/ E & ( for v1 being object st v1 in (the_Vertices_of G1) \ V holds
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) ) ) )now for x1, x2 being object st x1 in dom h & x2 in dom h & h . x1 = h . x2 holds
x1 = x2let x1,
x2 be
object ;
( x1 in dom h & x2 in dom h & h . x1 = h . x2 implies x1 = x2 )assume A43:
(
x1 in dom h &
x2 in dom h &
h . x1 = h . x2 )
;
x1 = x2then consider w1 being
Element of
(the_Vertices_of G1) \ V such that A44:
x1 = [{(the_Edges_of G2),(the_Edges_of G3)},w1]
by A4;
consider w2 being
Element of
(the_Vertices_of G1) \ V such that A45:
x2 = [{(the_Edges_of G2),(the_Edges_of G3)},w2]
by A4, A43;
w1 =
[{(the_Edges_of G2),(the_Edges_of G3)},w1] `2
.=
h . x1
by A4, A43, A44
.=
[{(the_Edges_of G2),(the_Edges_of G3)},w2] `2
by A4, A43, A45
.=
w2
;
hence
x1 = x2
by A44, A45;
verum end; then A46:
h is
one-to-one
by FUNCT_1:def 4;
thus card ((the_Vertices_of G1) \ V) =
card ((the_Vertices_of G3) \ V)
by Th98
.=
card E
by A4, A9, A46, CARD_1:70
;
( E misses the_Edges_of G3 & the_Edges_of G4 = (the_Edges_of G3) \/ E & ( for v1 being object st v1 in (the_Vertices_of G1) \ V holds
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) ) ) )thus
E misses the_Edges_of G3
by A16;
( the_Edges_of G4 = (the_Edges_of G3) \/ E & ( for v1 being object st v1 in (the_Vertices_of G1) \ V holds
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) ) ) )thus
the_Edges_of G4 = (the_Edges_of G3) \/ E
;
for v1 being object st v1 in (the_Vertices_of G1) \ V holds
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) )let v1 be
object ;
( v1 in (the_Vertices_of G1) \ V implies ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) ) )assume A47:
v1 in (the_Vertices_of G1) \ V
;
ex e1 being object st
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) )set e1 =
[{(the_Edges_of G2),(the_Edges_of G3)},v1];
take e1 =
[{(the_Edges_of G2),(the_Edges_of G3)},v1];
( e1 in E & e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) )thus A48:
e1 in E
by A47;
( e1 Joins v1,v,G4 & ( for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2 ) )then
e1 in (the_Edges_of G3) \/ E
by XBOOLE_0:def 3;
then A49:
e1 in the_Edges_of G4
;
A50:
e1 in dom (E --> v)
by A48;
A51:
(the_Source_of G4) . e1 =
s . e1
.=
h . e1
by A4, A48, FUNCT_4:13
.=
e1 `2
by A4, A48
.=
v1
;
(the_Target_of G4) . e1 =
t . e1
.=
(E --> v) . e1
by A50, FUNCT_4:13
.=
v
by A48, FUNCOP_1:7
;
hence
e1 Joins v1,
v,
G4
by A49, A51, GLIB_000:def 13;
for e2 being object st e2 Joins v1,v,G4 holds
e1 = e2let e2 be
object ;
( e2 Joins v1,v,G4 implies e1 = e2 )assume A52:
e2 Joins v1,
v,
G4
;
e1 = e2
not
e2 Joins v1,
v,
G3
then A53:
not
e2 in the_Edges_of G3
by A52, GLIB_006:72;
e2 in the_Edges_of G4
by A52, GLIB_000:def 13;
then
e2 in (the_Edges_of G3) \/ E
;
then A54:
e2 in E
by A53, XBOOLE_0:def 3;
then consider w being
Element of
(the_Vertices_of G1) \ V such that A55:
e2 = [{(the_Edges_of G2),(the_Edges_of G3)},w]
;
(the_Source_of G4) . e2 =
s . e2
.=
h . e2
by A4, A54, FUNCT_4:13
.=
[{(the_Edges_of G2),(the_Edges_of G3)},w] `2
by A4, A54, A55
.=
w
;
then A56:
(
v = w or
v1 = w )
by A52, GLIB_000:def 13;
v1 = w
hence
e1 = e2
by A55;
verum end; then reconsider G4 =
G4 as
addAdjVertexAll of
G3,
v,
(the_Vertices_of G1) \ V by A29, GLIB_007:def 4;
take
G4
;
G4 is GraphComplement of G2now ( the_Vertices_of G4 = the_Vertices_of G2 & the_Edges_of G4 misses the_Edges_of G2 & ( for u, w being Vertex of G2 st u <> w holds
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st e1 Joins u,w,G2 ) ) ) )thus the_Vertices_of G4 =
(the_Vertices_of G3) \/ {v}
.=
(the_Vertices_of G1) \/ {v}
by Th98
.=
the_Vertices_of G2
by A1, GLIB_007:def 4
;
( the_Edges_of G4 misses the_Edges_of G2 & ( for u, w being Vertex of G2 st u <> w holds
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b5 Joins e1,b4,G2 ) ) ) )
(the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } misses the_Edges_of G2
by A1, A21, XBOOLE_1:70;
hence
the_Edges_of G4 misses the_Edges_of G2
;
for u, w being Vertex of G2 st u <> w holds
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b5 Joins e1,b4,G2 ) )let u,
w be
Vertex of
G2;
( u <> w implies ( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b3 Joins e1,b2,G2 ) ) )assume A57:
u <> w
;
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b3 Joins e1,b2,G2 ) )hereby ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b3 Joins e1,b2,G2 )
given e1 being
object such that A58:
e1 Joins u,
w,
G2
;
for e2 being object holds not e2 Joins u,w,G4per cases
( e1 Joins u,w,G1 or not e1 in the_Edges_of G1 )
by A58, GLIB_006:72;
suppose A59:
e1 Joins u,
w,
G1
;
for e2 being object holds not e2 Joins u,w,G4then
(
u is
Vertex of
G1 &
w is
Vertex of
G1 )
by GLIB_000:13;
then A60:
for
e2 being
object holds not
e2 Joins u,
w,
G3
by A57, A59, Th98;
(
u <> v &
w <> v )
by A1, A59, GLIB_000:13;
hence
for
e2 being
object holds not
e2 Joins u,
w,
G4
by A29, A60, GLIB_007:49;
verum end; suppose A61:
not
e1 in the_Edges_of G1
;
for e2 being object holds not e2 Joins u,w,G4A62:
the_Edges_of G2 = (the_Edges_of G1) \/ (G2 .edgesBetween (V,{v}))
by A1, GLIB_007:59;
e1 in the_Edges_of G2
by A58, GLIB_000:def 13;
then
e1 in G2 .edgesBetween (
V,
{v})
by A61, A62, XBOOLE_0:def 3;
then
e1 SJoins V,
{v},
G2
by GLIB_000:def 30;
then
( (
(the_Source_of G2) . e1 in V &
(the_Target_of G2) . e1 in {v} ) or (
(the_Source_of G2) . e1 in {v} &
(the_Target_of G2) . e1 in V ) )
by GLIB_000:def 15;
then A63:
( (
u in V &
w in {v} ) or (
u in {v} &
w in V ) )
by A58, GLIB_000:def 13;
then A64:
( (
u = v &
w in V ) or (
u in V &
w = v ) )
by TARSKI:def 1;
thus
for
e2 being
object holds not
e2 Joins u,
w,
G4
verumproof
given e2 being
object such that A65:
e2 Joins u,
w,
G4
;
contradiction
A66:
not
e2 in the_Edges_of G3
e2 in the_Edges_of G4
by A65, GLIB_000:def 13;
then
e2 in (the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
;
then A67:
e2 in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A66, XBOOLE_0:def 3;
then consider x being
Element of
(the_Vertices_of G1) \ V such that A68:
e2 = [{(the_Edges_of G2),(the_Edges_of G3)},x]
;
(the_Source_of G4) . e2 =
s . e2
.=
h . e2
by A4, A67, FUNCT_4:13
.=
[{(the_Edges_of G2),(the_Edges_of G3)},x] `2
by A4, A67, A68
.=
x
;
then
(
(the_Source_of G4) . e2 in the_Vertices_of G1 & not
(the_Source_of G4) . e2 in V )
by A3, XBOOLE_0:def 5;
end; end; end;
end; assume A69:
for
e2 being
object holds not
e2 Joins u,
w,
G4
;
ex e1 being object st b3 Joins e1,b2,G2A70:
for
e2 being
object holds not
e2 Joins u,
w,
G3
by A69, GLIB_006:70;
per cases
( u = v or w = v or ( u <> v & w <> v ) )
;
suppose A71:
u = v
;
ex e1 being object st b3 Joins e1,b2,G2A72:
not
w in {v}
by A57, A71, TARSKI:def 1;
w in V
proof
assume A73:
not
w in V
;
contradiction
the_Vertices_of G2 = (the_Vertices_of G1) \/ {v}
by A1, GLIB_007:def 4;
then
w in the_Vertices_of G1
by A72, XBOOLE_0:def 3;
then A74:
w in (the_Vertices_of G1) \ V
by A73, XBOOLE_0:def 5;
set e1 =
[{(the_Edges_of G2),(the_Edges_of G3)},w];
A75:
[{(the_Edges_of G2),(the_Edges_of G3)},w] in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A74;
then A76:
[{(the_Edges_of G2),(the_Edges_of G3)},w] in dom ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v)
;
[{(the_Edges_of G2),(the_Edges_of G3)},w] in (the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A75, XBOOLE_0:def 3;
then A77:
[{(the_Edges_of G2),(the_Edges_of G3)},w] in the_Edges_of G4
;
A78:
(the_Source_of G4) . [{(the_Edges_of G2),(the_Edges_of G3)},w] =
s . [{(the_Edges_of G2),(the_Edges_of G3)},w]
.=
h . [{(the_Edges_of G2),(the_Edges_of G3)},w]
by A4, A75, FUNCT_4:13
.=
[{(the_Edges_of G2),(the_Edges_of G3)},w] `2
by A4, A75
.=
w
;
(the_Target_of G4) . [{(the_Edges_of G2),(the_Edges_of G3)},w] =
t . [{(the_Edges_of G2),(the_Edges_of G3)},w]
.=
( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v) . [{(the_Edges_of G2),(the_Edges_of G3)},w]
by A76, FUNCT_4:13
.=
v
by A75, FUNCOP_1:7
;
then
[{(the_Edges_of G2),(the_Edges_of G3)},w] Joins v,
w,
G4
by A77, A78, GLIB_000:def 13;
hence
contradiction
by A69, A71;
verum
end; then consider e1 being
object such that A79:
(
e1 in E0 &
e1 Joins w,
v,
G2 )
and
for
e2 being
object st
e2 Joins w,
v,
G2 holds
e1 = e2
by A2;
take e1 =
e1;
e1 Joins u,w,G2thus
e1 Joins u,
w,
G2
by A71, A79, GLIB_000:14;
verum end; suppose A80:
w = v
;
ex e1 being object st b3 Joins e1,b2,G2A81:
not
u in {v}
by A57, A80, TARSKI:def 1;
u in V
proof
assume A82:
not
u in V
;
contradiction
the_Vertices_of G2 = (the_Vertices_of G1) \/ {v}
by A1, GLIB_007:def 4;
then
u in the_Vertices_of G1
by A81, XBOOLE_0:def 3;
then A83:
u in (the_Vertices_of G1) \ V
by A82, XBOOLE_0:def 5;
set e1 =
[{(the_Edges_of G2),(the_Edges_of G3)},u];
A84:
[{(the_Edges_of G2),(the_Edges_of G3)},u] in { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A83;
then A85:
[{(the_Edges_of G2),(the_Edges_of G3)},u] in dom ( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v)
;
[{(the_Edges_of G2),(the_Edges_of G3)},u] in (the_Edges_of G3) \/ { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum }
by A84, XBOOLE_0:def 3;
then A86:
[{(the_Edges_of G2),(the_Edges_of G3)},u] in the_Edges_of G4
;
A87:
(the_Source_of G4) . [{(the_Edges_of G2),(the_Edges_of G3)},u] =
s . [{(the_Edges_of G2),(the_Edges_of G3)},u]
.=
h . [{(the_Edges_of G2),(the_Edges_of G3)},u]
by A4, A84, FUNCT_4:13
.=
[{(the_Edges_of G2),(the_Edges_of G3)},u] `2
by A4, A84
.=
u
;
(the_Target_of G4) . [{(the_Edges_of G2),(the_Edges_of G3)},u] =
t . [{(the_Edges_of G2),(the_Edges_of G3)},u]
.=
( { [{(the_Edges_of G2),(the_Edges_of G3)},w] where w is Element of (the_Vertices_of G1) \ V : verum } --> v) . [{(the_Edges_of G2),(the_Edges_of G3)},u]
by A85, FUNCT_4:13
.=
v
by A84, FUNCOP_1:7
;
then
[{(the_Edges_of G2),(the_Edges_of G3)},u] Joins u,
v,
G4
by A86, A87, GLIB_000:def 13;
hence
contradiction
by A69, A80;
verum
end; then consider e1 being
object such that A88:
(
e1 in E0 &
e1 Joins u,
v,
G2 )
and
for
e2 being
object st
e2 Joins u,
v,
G2 holds
e1 = e2
by A2;
take e1 =
e1;
e1 Joins u,w,G2thus
e1 Joins u,
w,
G2
by A80, A88;
verum end; suppose
(
u <> v &
w <> v )
;
ex e1 being object st b3 Joins e1,b2,G2then A89:
( not
u in {v} & not
w in {v} )
by TARSKI:def 1;
the_Vertices_of G2 = (the_Vertices_of G1) \/ {v}
by A1, GLIB_007:def 4;
then
(
u is
Vertex of
G1 &
w is
Vertex of
G1 )
by A89, XBOOLE_0:def 3;
then consider e1 being
object such that A90:
e1 Joins u,
w,
G1
by A57, A70, Th98;
take e1 =
e1;
e1 Joins u,w,G2thus
e1 Joins u,
w,
G2
by A90, GLIB_006:70;
verum end; end; end; hence
G4 is
GraphComplement of
G2
by Th98;
verum end; suppose A91:
(the_Vertices_of G1) \ V = {}
;
ex G4 being addAdjVertexAll of G3,v,(the_Vertices_of G1) \ V st G4 is GraphComplement of G2take G4 = the
addAdjVertexAll of
G3,
v,
(the_Vertices_of G1) \ V;
G4 is GraphComplement of G2A92:
G4 is
addVertex of
G3,
v
by A91, GLIB_007:55;
now ( the_Vertices_of G4 = the_Vertices_of G2 & the_Edges_of G4 misses the_Edges_of G2 & ( for u, w being Vertex of G2 st u <> w holds
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st e1 Joins u,w,G2 ) ) ) )thus the_Vertices_of G4 =
(the_Vertices_of G3) \/ {v}
by A92, GLIB_006:def 10
.=
(the_Vertices_of G1) \/ {v}
by Th98
.=
the_Vertices_of G2
by A1, GLIB_007:def 4
;
( the_Edges_of G4 misses the_Edges_of G2 & ( for u, w being Vertex of G2 st u <> w holds
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b5 Joins e1,b4,G2 ) ) ) )
the_Edges_of G3 = the_Edges_of G4
by A92, GLIB_006:def 10;
hence
the_Edges_of G4 misses the_Edges_of G2
by A1;
for u, w being Vertex of G2 st u <> w holds
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b5 Joins e1,b4,G2 ) )let u,
w be
Vertex of
G2;
( u <> w implies ( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b3 Joins e1,b2,G2 ) ) )assume A93:
u <> w
;
( ( ex e1 being object st e1 Joins u,w,G2 implies for e2 being object holds not e2 Joins u,w,G4 ) & ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b3 Joins e1,b2,G2 ) )hereby ( ( for e2 being object holds not e2 Joins u,w,G4 ) implies ex e1 being object st b3 Joins e1,b2,G2 )
given e1 being
object such that A94:
e1 Joins u,
w,
G2
;
for e2 being object holds not e2 Joins u,w,G4per cases
( e1 Joins u,w,G1 or not e1 in the_Edges_of G1 )
by A94, GLIB_006:72;
suppose A96:
not
e1 in the_Edges_of G1
;
for e2 being object holds not e2 Joins u,w,G4A97:
the_Edges_of G2 = (the_Edges_of G1) \/ (G2 .edgesBetween (V,{v}))
by A1, GLIB_007:59;
e1 in the_Edges_of G2
by A94, GLIB_000:def 13;
then
e1 in G2 .edgesBetween (
V,
{v})
by A96, A97, XBOOLE_0:def 3;
then
e1 SJoins V,
{v},
G2
by GLIB_000:def 30;
then
( (
(the_Source_of G2) . e1 in V &
(the_Target_of G2) . e1 in {v} ) or (
(the_Source_of G2) . e1 in {v} &
(the_Target_of G2) . e1 in V ) )
by GLIB_000:def 15;
then
( (
u in V &
w in {v} ) or (
u in {v} &
w in V ) )
by A94, GLIB_000:def 13;
then
( (
u in V &
w = v ) or (
u = v &
w in V ) )
by TARSKI:def 1;
then
( not
u in the_Vertices_of G3 or not
w in the_Vertices_of G3 )
by A1, Th98;
then
for
e2 being
object holds not
e2 Joins u,
w,
G3
by GLIB_000:13;
hence
for
e2 being
object holds not
e2 Joins u,
w,
G4
by A92, GLIB_006:87;
verum end; end;
end; assume
for
e2 being
object holds not
e2 Joins u,
w,
G4
;
ex e1 being object st b3 Joins e1,b2,G2then A98:
for
e2 being
object holds not
e2 Joins u,
w,
G3
by A92, GLIB_006:87;
A99:
the_Vertices_of G2 = (the_Vertices_of G1) \/ {v}
by A1, GLIB_007:def 4;
the_Vertices_of G1 c= V
by A91, XBOOLE_1:37;
then A100:
V = the_Vertices_of G1
by XBOOLE_0:def 10;
per cases
( u = v or w = v or ( u <> v & w <> v ) )
;
suppose A101:
u = v
;
ex e1 being object st b3 Joins e1,b2,G2then
not
w in {v}
by A93, TARSKI:def 1;
then
w in the_Vertices_of G1
by A99, XBOOLE_0:def 3;
then consider e1 being
object such that A102:
(
e1 in E0 &
e1 Joins w,
v,
G2 )
and
for
e2 being
object st
e2 Joins w,
v,
G2 holds
e1 = e2
by A2, A100;
take e1 =
e1;
e1 Joins u,w,G2thus
e1 Joins u,
w,
G2
by A101, A102, GLIB_000:14;
verum end; suppose A103:
w = v
;
ex e1 being object st b3 Joins e1,b2,G2then
not
u in {v}
by A93, TARSKI:def 1;
then
u in the_Vertices_of G1
by A99, XBOOLE_0:def 3;
then consider e1 being
object such that A104:
(
e1 in E0 &
e1 Joins u,
v,
G2 )
and
for
e2 being
object st
e2 Joins u,
v,
G2 holds
e1 = e2
by A2, A100;
take e1 =
e1;
e1 Joins u,w,G2thus
e1 Joins u,
w,
G2
by A103, A104;
verum end; suppose
(
u <> v &
w <> v )
;
ex e1 being object st b3 Joins e1,b2,G2then
( not
u in {v} & not
w in {v} )
by TARSKI:def 1;
then
(
u is
Vertex of
G1 &
w is
Vertex of
G1 )
by A99, XBOOLE_0:def 3;
then consider e1 being
object such that A105:
e1 Joins u,
w,
G1
by A93, A98, Th98;
take e1 =
e1;
e1 Joins u,w,G2thus
e1 Joins u,
w,
G2
by A105, GLIB_006:70;
verum end; end; end; hence
G4 is
GraphComplement of
G2
by Th98;
verum end; end;