\newchapter{Graph theory}

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Graph is a group of nodes, some of them may be connected with each other, some are not.
One of the popular examples is the map of country: there are cities and roads.
"Cities" are called "nodes" or "vertices" in mathematics lingo, while "roads" are called "edges".
Another popular example of graph is computer network, including Internet.
Computer network is graph indeed, but it's closer to "sparse graph", because for the most part, computer networks are trees.

\input{graph/clique/main}

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