/sci/ - Science & Math

>>12664230
It can help find a lower bound, but I have no idea how to prove if it's best possible. [math]K_7[/math] has 21 edges. Divide by 7. We want three edges per row. Fortunately, that's totally possible, since a 3-clique has three edges. So put three filled cells in each row.

Here's my attempt. If this doesn't actually work, tell me.