Here is a list of all the current tags in the system, ordered by the number of problems with that tag. This is a work in progress - if you have suggestions of new tags to be added, or that certain tags should be added or removed from a problem, please let me know.

Sort alphabetically or by total number or by number solved or by number unsolved.

• number theory : 171 solved out of 533
• graph theory : 121 solved out of 271
• ramsey theory : 42 solved out of 104
• geometry : 35 solved out of 103
• additive combinatorics : 39 solved out of 89
• analysis : 32 solved out of 58
• chromatic number : 25 solved out of 57
• distances : 12 solved out of 52
• primes : 10 solved out of 49
• unit fractions : 24 solved out of 49
• combinatorics : 24 solved out of 44
• divisors : 12 solved out of 31
• sidon sets : 6 solved out of 28
• additive basis : 8 solved out of 27
• hypergraphs : 10 solved out of 27
• arithmetic progressions : 9 solved out of 24
• cycles : 11 solved out of 24
• irrationality : 6 solved out of 23
• binomial coefficients : 5 solved out of 22
• turan number : 7 solved out of 21
• set theory : 6 solved out of 21
• factorials : 7 solved out of 20
• covering systems : 9 solved out of 18
• discrepancy : 9 solved out of 16
• powerful : 3 solved out of 14
• convex : 4 solved out of 12
• polynomials : 8 solved out of 12
• iterated functions : 1 solved out of 9
• probability : 5 solved out of 9
• complete sequences : 2 solved out of 8
• primitive sets : 2 solved out of 7
• diophantine approximation : 4 solved out of 7
• intersecting family : 4 solved out of 5
• base representations : 0 solved out of 5
• group theory : 1 solved out of 4
• squares : 1 solved out of 4
• powers : 0 solved out of 4
• planar graphs : 1 solved out of 3
• topology : 2 solved out of 2

In total there are 1105 problems in the database of which 420 have been solved.