combinatorics / Discrepancy Theory

Erdős Problem #176

Let $N(k, \ell)$ be the least $N$ such that every $f : [N] \to \{-1, 1\}$ has a $k$-term arithmetic progression $P$ with $|\sum_{n \in P} f(n)| \ge \ell$. In particular, is $N(k, 2) \le C^k$?

11Significance / 100
1Frontier events
0Verification tasks
0Recorded attempts

Temporal state

Current frontier

No reconciled state yet.

Append-only history

Frontier timeline

combinatoricsJun 21, 2026Significance 11/100Registry: lean verified

Erdős Problem #176

Prior state unknownproved

a polynomial bound for N(k,2), stronger than the exponential bound asked for; the two-parameter problem remains open

SourceReplayReproducedFormal proofStatement auditExternal checkExpert reviewPeer review

Research memory

Claims and attempts

Scoped claims

Source authenticated

Let $N(k, \ell)$ be the least $N$ such that every $f : [N] \to \{-1, 1\}$ has a $k$-term arithmetic progression $P$ with $|\sum_{n \in P} f(n)| \ge \ell$. In particular, is $N(k, 2) \le C^k$?

a polynomial bound for N(k,2), stronger than the exponential bound asked for; the two-parameter problem remains open

Recorded attempts

Evidence graph

Connected research record

No public relationships recorded yet.