
theorem Th92:
  for G being _Graph, v,w being Vertex of G st v is with_min_in_degree
  holds v.inDegree() c= w.inDegree()
proof
  let G be _Graph, v,w be Vertex of G;
  assume v is with_min_in_degree;
  then v.inDegree() = G.minInDegree();
  then consider v0 being Vertex of G such that
    A1: v0.inDegree() = v.inDegree() and
    A2: for u being Vertex of G holds v0.inDegree() c= u.inDegree() by Th37;
  thus thesis by A1, A2;
end;
