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

intersection of subgroups

For subgroups $H, K \le G$ , the set $H \cap K$ of elements common to both -- always itself a subgroup of $G$ .

Loading interactive…

Examples

In $D_4$ , two different order-2 reflection subgroups intersect in just $\{e\}$ .