##### Wikipedia

**Mycielskian**

In the mathematical area of graph theory, the **Mycielskian** or **Mycielski graph** of an undirected graph is a larger graph formed from it by a construction of . The construction preserves the property of being triangle-free but increases the chromatic number; by applying the construction repeatedly to a triangle-free starting graph, Mycielski showed that there exist triangle-free graphs with arbitrarily large chromatic number.