let G2 be inducedSubgraph of G,(G .reachableFrom v); G2 is Component-like
A1:
the_Vertices_of G2 = G .reachableFrom v
by GLIB_000:def 39;
A2:
the_Edges_of G2 = G .edgesBetween (G .reachableFrom v)
by GLIB_000:def 39;
now let x,
y be
Vertex of
G2;
ex W being Walk of G2 st W is_Walk_from x,yconsider W1R being
Walk of
G such that A17:
W1R is_Walk_from v,
x
by A1, Def5;
consider W2 being
Walk of
G such that A18:
W2 is_Walk_from v,
y
by A1, Def5;
set W1 =
W1R .reverse() ;
set W =
(W1R .reverse() ) .append W2;
A19:
W1R .reverse() is_Walk_from x,
v
by A17, GLIB_001:24;
then A20:
(W1R .reverse() ) .append W2 is_Walk_from x,
y
by A18, GLIB_001:32;
A21:
(W1R .reverse() ) .last() = v
by A19, GLIB_001:def 23;
then A22:
v in (W1R .reverse() ) .vertices()
by GLIB_001:89;
A23:
((W1R .reverse() ) .append W2) .edges() c= G .edgesBetween (((W1R .reverse() ) .append W2) .vertices() )
by GLIB_001:110;
W2 .first() = v
by A18, GLIB_001:def 23;
then
((W1R .reverse() ) .append W2) .vertices() = ((W1R .reverse() ) .vertices() ) \/ (W2 .vertices() )
by A21, GLIB_001:94;
then A24:
v in ((W1R .reverse() ) .append W2) .vertices()
by A22, XBOOLE_0:def 3;
then
G .edgesBetween (((W1R .reverse() ) .append W2) .vertices() ) c= G .edgesBetween (the_Vertices_of G2)
by A1, Lm4, GLIB_000:39;
then
((W1R .reverse() ) .append W2) .edges() c= G .edgesBetween (the_Vertices_of G2)
by A23, XBOOLE_1:1;
then reconsider W =
(W1R .reverse() ) .append W2 as
Walk of
G2 by A1, A2, A24, Lm4, GLIB_001:171;
take W =
W;
W is_Walk_from x,ythus
W is_Walk_from x,
y
by A20, GLIB_001:20;
verum end;
then
G2 is connected
by Def1;
hence
G2 is Component-like
by A3, Def7; verum