let G1, G2 be _Graph; :: thesis: ( G2 is G1 -Disomorphic implies G1 .allSpanningTrees() ,G2 .allSpanningTrees() are_Disomorphic )
assume G2 is G1 -Disomorphic ; :: thesis: G1 .allSpanningTrees() ,G2 .allSpanningTrees() are_Disomorphic
then consider F being PGraphMapping of G1,G2 such that
A1: F is Disomorphism by GLIB_010:def 24;
set f = (SG2SGFunc F) | (G1 .allSpanningTrees());
A2: dom ((SG2SGFunc F) | (G1 .allSpanningTrees())) = G1 .allSpanningTrees() by FUNCT_2:def 1;
A3: rng ((SG2SGFunc F) | (G1 .allSpanningTrees())) = G2 .allSpanningTrees() by A1, Th180;
SG2SGFunc F is one-to-one by A1, Th31;
then A4: (SG2SGFunc F) | (G1 .allSpanningTrees()) is one-to-one by FUNCT_1:52;

now :: thesis: for G being _Graph st G in G1 .allSpanningTrees() holds
((SG2SGFunc F) | (G1 .allSpanningTrees())) . G is b₁ -Disomorphic _Graph

let G be _Graph; :: thesis: ( G in G1 .allSpanningTrees() implies ((SG2SGFunc F) | (G1 .allSpanningTrees())) . G is G -Disomorphic _Graph )
assume A5: G in G1 .allSpanningTrees() ; :: thesis: ((SG2SGFunc F) | (G1 .allSpanningTrees())) . G is G -Disomorphic _Graph
then reconsider H = G as spanning acyclic plain Subgraph of G1 by Th168;
reconsider F9 = F | H as PGraphMapping of H, rng (F | H) by GLIBPRE1:88;
A6: ((SG2SGFunc F) | (G1 .allSpanningTrees())) . G = (SG2SGFunc F) . G by A5, FUNCT_1:49
.= rng (F | H) by Def5 ;
F9 is Disomorphism by A1, GLIBPRE1:110;
hence ((SG2SGFunc F) | (G1 .allSpanningTrees())) . G is G -Disomorphic _Graph by A6, GLIB_010:def 24; :: thesis: verum

end;

hence G1 .allSpanningTrees() ,G2 .allSpanningTrees() are_Disomorphic by A2, A3, A4, GLIB_015:def 12; :: thesis: verum