Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

vertex

A single point or node in a graph or geometric figure, where edges or sides meet.

Examples

A Cayley graph has one vertex for each group element.