@MartinSleziak The tag geometry was removed by the OP. The question is still missing a top-level tag (and perhaps some other suitable tags can be chosen).
@MartinSleziak, thanks for your suggestion. I'm sorry. I'm new here and I'm not familar with it. Now I have removed this tag but I'm still not sure what other tags should I use :) — Yachy2 mins ago
@Yachy Some tags which I would consider as a possible candidates are (mg.metric-geometry), (convex-geometry) or (sumsets). But I do not consider myself familiar with this are well enough to be able to judge which tags are actually suitable. In any case, if we want to discuss the choice of tags further, perhaps we could continue in chat rather than here in comments. — Martin Sleziak48 secs ago
