reserve G, G1, G2 for _Graph, H for Subgraph of G;

theorem Th106:
  createGraph([#]the_Vertices_of G) in G.allSpanningForests()
proof
  set H = createGraph([#]the_Vertices_of G);
  A1: H in G.allForests() by Th81;
  A2: H in G.allSpanningSG() by Th63;
  G.allSpanningForests() = G.allSpanningSG() /\ G.allForests() by Th103;
  hence thesis by A1, A2, XBOOLE_0:def 4;
end;
