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Problems have always been an essential part of my mathematical life. A well-chosen problem can isolate an essential difficulty in a particular area, serving as a benchmark against which progress in this area can be measured. It might be like a 'marshmallow', serving as a tasty tidbit supplying a few moments of fleeting enjoyment. Or it might be like an 'acorn', requiring deep and subtle new insights from which a mighty oak can develop. […]

In this note I would like to describe a variety of my problems which I would classify as my favorites. Of course, I can't guarantee that they are all 'acorns', but because many have thwarted the efforts of the best mathematicians for many decades (and have often acquired a cash reward for their solutions), it may indicate that new ideas will be needed, which can, in turn, lead to more general results, and naturally, to further new problems.

In this way, the cycle of life in mathematics continues forever.

Paul Erdős, Some of my favorite problems and results, 1997
There are 634 problems in the database of which 182 have been solved.
RECENT PROGRESS
  • 20-05-2024: 429 (Sparse Admissible Sets and a Problem of Erdős and Graham - Weisenberg arXiv)
  • 19-05-2024: 121 (On product representations of squares - Tao arXiv)
  • 19-05-2024: 314 (On differences of two harmonic numbers - Steinerberger arXiv)
  • 15-05-2024: 29 (An explicit economical additive basis - Jain, Pham, Sawhney, and Zakharov arXiv)
  • 13-05-2024: 268 (On the set of points represented by harmonic subseries - Kovać arXiv)
  • 24-04-2024: 297 (A question of Erdős and Graham on Egyptian fractions - Conlon, Fox, He, Mubayi, Pham, Suk, and Verstraëte arXiv)
  • 10-04-2024: 585 (Edge-disjoint cycles with the same vertex set - Chakraborti, Janzer, Methuku, and Montgomery arXiv)
  • 10-04-2024: 47 294 297 300 305 310 (On further questions regarding unit fractions - Liu and Sawhney arXiv)
  • 25-03-2024: 297 (On a problem involving unit fractions - Steinerberger arXiv)
  • 28-02-2024: 3 (Improved Bounds for Szemerédi's Theorem - Leng, Sah, and Sawhney arXiv)
  • 25-01-2024: 208 (Squarefree numbers in short intervals - Pandey arXiv)
  • 19-01-2024: 213 (On integer distance sets - Greenfeld, Iliopoulou, and Peluse arXiv)
  • 02-01-2024: 549 (On the Ramsey number of the double star - Dubó and Stein arXiv)