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
  for m being odd Element of NAT, x being Element of NAT st x in dom W
  .cut(1,m) & m <= len W holds W.cut(1,m).x = W.x by Lm23;
