Def bi-tree(T;to;from)
Def == bi-graph(T;to;from)
Def == & (i,j:|T|.
Def == & (p:Edge(T) List. 
Def == & (lconnects(p;i;j) & (q:Edge(T) List. lconnects(q;i;j)  q = p))
Def == & (L:|T| List. i:|T|. (i  L))
Def == & |T|

is mentioned by

Thm* T:(Id), to,from:(|T|(IdLnk List)), f:(Edge(T)). Thm* bi-tree(T;to;from) Thm*  Thm* spanner(f;T;to;from) Thm*  Thm* (i,j:|T|. Thm* (spanner-root(f;T;to;from;i)  spanner-root(f;T;to;from;j)  i = j)	[spanner-root-unique]
Thm* T:(Id), to,from:(|T|(IdLnk List)), f:(Edge(T)). Thm* bi-tree(T;to;from) Thm*  Thm* spanner(f;T;to;from)  (i:|T|. spanner-root(f;T;to;from;i))	[spanner-root-exists]
Thm* T:(Id), to,from:(|T|(IdLnk List)). Thm* bi-tree(T;to;from)  (n:. p:Edge(T) List. lpath(p)  ||p||n)	[bi-tree-diameter]

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