Erdős Problem a Daythe open tracker

Erdős Problem #274
Herzog-Schönheim conjecture

OPENdatabase updated 2025-08-31

No proof or disproof is known, and it isn't known whether a finite computation could settle it.

What the community database records, not our verdict. erdosproblems.com no longer shows statuses (why).

An exact covering of a group `G` is a finite collection of subgroups `{H_1, ..., H_k}` and representative `{g_1, ..., g_k}` such that the cosets `g_iH_i` are pairwise disjoint and their union covers `G`. Note that this differs from `Partition (α := Subgroup G)` because the covering condition there invokes `Subgroup.sup` which is subgroup generation and thus stronger than union. This definition is easier to use in this context than the alternative `Partition (α := Set G)`, which lacks subgroup de

If \(G\) is a group, can there exist an exact covering of \(G\) by more than one coset of different sizes? (i.e. each element is contained in exactly one of the cosets.) The conjectured answer is no: in every such exact covering, two of the subgroups have the same cardinality.
Statement as formalized in Formal Conjectures (Google DeepMind, Apache-2.0) · their label: research open · 2 further variants / known partial results in the Lean file. The authoritative wording is on erdosproblems.com/274.
Prizenone
Topicsgroup theory, covering systems
Statement in LeanFormal Conjectures
Solution in Leanno
Original pageerdosproblems.com/274
WORKING REPORT BY THIS SITE · JUL 29, 2026

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Proved, with a uniform exact bound and standalone verification, that every finite direct power \(A_5^r\) satisfies the Herzog–Schönheim conjecture; the general problem remains open.

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