cs.DM cs.DM

7 278 601 292 779 396 715. That’s exactly how many unlabeled chordal graphs, graphs with no induced cycles of length four or more, can be built on twenty vertices. This number isn’t a puzzle for a supercomputer; it’s the exact output of a new algorithm that treats symmetry as a tool, not an obstacle.

A family tree becomes a tangle if you account for adopted children and remarriages. Evolution often resembles such a tangle: although the Standard Model, the traditional view of divergent evolution where species branch like a tree, paints a neat tree of species, in reality genes travel not only by inheritance but also directly between unrelated organisms — a process…