Definition
Plain language
A specific Erdős open problem from 1970 about sumsets of digit-restricted integers, solved autonomously by an AI system in 2026.
As stated in the literature
Erdős problem 125, asking about the lower density of A+B where A consists of integers with only 0s and 1s in base 3 and B of integers with only 0s and 1s in base 4; resolved (under one density convention) by a DeepMind Lean-proof-search agent.
Why it matters: Resolving a long-standing named open problem is a concrete demonstration that AI systems can contribute new mathematics, not just rederive textbook results.
For example, Erdős #125 asks about how dense the sumset becomes when you add together two sets of integers whose digits are restricted in different bases.