is mentioned by

Thm* G:(Id), to,from:(|G|(IdLnk List)), l:Edge(G). Thm* bi-graph(G;to;from)  lnk-inv(l)  Edge(G)	[inv-is-edge]
Def inverse(l) == lnk-inv(l)	[bi-graph-inv]
Def bi-graph(G;to;from) Def == i:|G|.  Def == (lto(i).destination(l) = i Def == & (G(source(l))) Def == & (l  from(source(l))) Def == & (lnk-inv(l)  from(i))) Def == & (lfrom(i).source(l) = i Def == & & (G(destination(l))) Def == & & (l  to(destination(l))) Def == & & (lnk-inv(l)  to(i)))	[bi-graph]

In prior sections: mb event system 1 mb event system 2

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