reserve G,G1,G2 for _Graph;
reserve W,W1,W2 for Walk of G;
reserve e,x,y,z for set;
reserve v for Vertex of G;
reserve n,m for Element of NAT;

theorem Th29:
 for x,y,z being object holds
  W1 is_Walk_from x,y & W2 is_Walk_from y,z implies W1.append(W2)
  is_Walk_from x,z
by Lm11;
