| 1 | 18. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inr(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). (inr(j) s2@0)  (inl(j) s2@0)  j-the_graph- > *i@0) 19. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
( j:Vertices(the_graph). i@0-the_graph- > *j  non-trivial-loop(the_graph;j))

(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inl(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). i@0-the_graph- > *j  (inr(j) s2@0)) 20. i@0:Vertices(the_graph). L1 @ [i]-the_graph- > *i@0  non-trivial-loop(the_graph;i@0) 21. L1@0,L2:Vertices(the_graph) List.
L1 = (L1@0 @ L2)

( s1,s2:traversal(the_graph).
s = (s2 @ s1) traversal(the_graph)
& paren(Vertices(the_graph);s1) & paren(Vertices(the_graph);s2)
& ( j:Vertices(the_graph).
((inl(j) s1)  L1@0-the_graph- > *j)
& ((inl(j) s2)  L2-the_graph- > *j & L1@0-the_graph- > *j))) 22. L1@0: Vertices(the_graph) List 23. L2: Vertices(the_graph) List 24. (L1 @ [i]) = (L1@0 @ L2) 25. e: Vertices(the_graph) List 26. L1@0 = L1 27. [i] = L2 28. i:Vertices(the_graph). (inl(i) s)  L1-the_graph- > *i 29. j: Vertices(the_graph) 30. (inl(j) s)  L1-the_graph- > *j 31. (inl(j) s)  L1-the_graph- > *j 32. [i]-the_graph- > *j 33. (inl(j) s) 34. j1: Vertices(the_graph) 35. i-the_graph- > *j1 non-trivial-loop(the_graph;j1) | 2 steps |
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| 2 | 18. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inr(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). (inr(j) s2@0)  (inl(j) s2@0)  j-the_graph- > *i@0) 19. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
( j:Vertices(the_graph). i@0-the_graph- > *j  non-trivial-loop(the_graph;j))

(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inl(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). i@0-the_graph- > *j  (inr(j) s2@0)) 20. i@0:Vertices(the_graph). L1 @ [i]-the_graph- > *i@0  non-trivial-loop(the_graph;i@0) 21. L1@0,L2:Vertices(the_graph) List.
L1 = (L1@0 @ L2)

( s1,s2:traversal(the_graph).
s = (s2 @ s1) traversal(the_graph)
& paren(Vertices(the_graph);s1) & paren(Vertices(the_graph);s2)
& ( j:Vertices(the_graph).
((inl(j) s1)  L1@0-the_graph- > *j)
& ((inl(j) s2)  L2-the_graph- > *j & L1@0-the_graph- > *j))) 22. L1@0: Vertices(the_graph) List 23. L2: Vertices(the_graph) List 24. (L1 @ [i]) = (L1@0 @ L2) 25. e: Vertices(the_graph) List 26. L1@0 = L1 27. [i] = L2 28. i:Vertices(the_graph). (inl(i) s)  L1-the_graph- > *i 29. j: Vertices(the_graph) 30. (inl(j) s)  L1-the_graph- > *j 31. (inl(j) s)  L1-the_graph- > *j 32. [i]-the_graph- > *j 33. (inl(j) s) (([inl(i)] @ s2 @ [inr(i)]) @ s) = (nil @ [inl(i)] @ (s2 @ [inr(i)]) @ s) traversal(the_graph) | 1 step |
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| 3 | 18. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inr(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). (inr(j) s2@0)  (inl(j) s2@0)  j-the_graph- > *i@0) 19. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
( j:Vertices(the_graph). i@0-the_graph- > *j  non-trivial-loop(the_graph;j))

(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inl(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). i@0-the_graph- > *j  (inr(j) s2@0)) 20. i@0:Vertices(the_graph). L1 @ [i]-the_graph- > *i@0  non-trivial-loop(the_graph;i@0) 21. L1@0,L2:Vertices(the_graph) List.
L1 = (L1@0 @ L2)

( s1,s2:traversal(the_graph).
s = (s2 @ s1) traversal(the_graph)
& paren(Vertices(the_graph);s1) & paren(Vertices(the_graph);s2)
& ( j:Vertices(the_graph).
((inl(j) s1)  L1@0-the_graph- > *j)
& ((inl(j) s2)  L2-the_graph- > *j & L1@0-the_graph- > *j))) 22. L1@0: Vertices(the_graph) List 23. L2: Vertices(the_graph) List 24. (L1 @ [i]) = (L1@0 @ L2) 25. e: Vertices(the_graph) List 26. L1@0 = L1 27. [i] = L2 28. i:Vertices(the_graph). (inl(i) s)  L1-the_graph- > *i 29. j: Vertices(the_graph) 30. (inl(j) s)  L1-the_graph- > *j 31. (inl(j) s)  L1-the_graph- > *j 32. [i]-the_graph- > *j 33. (inl(j) s) i-the_graph- > *j | 1 step |
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| 4 | 18. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inr(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). (inr(j) s2@0)  (inl(j) s2@0)  j-the_graph- > *i@0) 19. i@0:Vertices(the_graph), s1,s2@0:traversal(the_graph).
( j:Vertices(the_graph). i@0-the_graph- > *j  non-trivial-loop(the_graph;j))

(([inl(i)] @ s2 @ [inr(i)]) @ s) = (s1 @ [inl(i@0)] @ s2@0) traversal(the_graph)

( j:Vertices(the_graph). i@0-the_graph- > *j  (inr(j) s2@0)) 20. i@0:Vertices(the_graph). L1 @ [i]-the_graph- > *i@0  non-trivial-loop(the_graph;i@0) 21. L1@0,L2:Vertices(the_graph) List.
L1 = (L1@0 @ L2)

( s1,s2:traversal(the_graph).
s = (s2 @ s1) traversal(the_graph)
& paren(Vertices(the_graph);s1) & paren(Vertices(the_graph);s2)
& ( j:Vertices(the_graph).
((inl(j) s1)  L1@0-the_graph- > *j)
& ((inl(j) s2)  L2-the_graph- > *j & L1@0-the_graph- > *j))) 22. L1@0: Vertices(the_graph) List 23. L2: Vertices(the_graph) List 24. (L1 @ [i]) = (L1@0 @ L2) 25. e: Vertices(the_graph) List 26. L1@0 = L1 27. [i] = L2 28. i:Vertices(the_graph). (inl(i) s)  L1-the_graph- > *i 29. j: Vertices(the_graph) 30. (inl(j) s)  L1-the_graph- > *j 31. [i]-the_graph- > *j & (inl(j) s) 32. (inr(j) (s2 @ [inr(i)]) @ s) inl(j) = inl(i) Vertices(the_graph)+Vertices(the_graph) (inl(j) s2) inl(j) = inr(i) Vertices(the_graph)+Vertices(the_graph) | 6 steps |