Editing Channel capacity (section)

==Shannon capacity of a graph==
{{main|Shannon capacity of a graph}}
If ''G'' is an [[undirected graph]], it can be used to define a communications channel in which the symbols are the graph vertices, and two codewords may be confused with each other if their symbols in each position are equal or adjacent. The computational complexity of finding the Shannon capacity of such a channel remains open, but it can be upper bounded by another important graph invariant, the [[Lovász number]].<ref>{{citation | first = László | last = Lovász | author-link = László Lovász | title = On the Shannon Capacity of a Graph | journal = [[IEEE Transactions on Information Theory]] | volume = IT-25 | issue = 1 | year = 1979 | pages = 1–7 | doi = 10.1109/tit.1979.1055985 }}.</ref>