Thickness-Two Graphs Part Two: More New Nine-Critical Graphs, Independence Ratio, Cloned Planar Graphs, and Singly and Doubly Outerplanar Graphs

Thickness-two graphs part one: New nine-

Thickness-two graphs part one: New nine-critical graphs, permuted layer graphs, and Catlin's graphs

✍ Debra L. Boutin; Ellen Gethner; Thom Sulanke 📂 Article 📅 2008 🏛 John Wiley and Sons 🌐 English ⚖ 605 KB

## Abstract The purpose of this article is to offer new insight and tools toward the pursuit of the largest chromatic number in the class of thicknesstwo graphs. At present, the highest chromatic number known for a thickness‐two graph is 9, and there is only one known color‐critical such graph. We