A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
used only for functions based on gamma, not functions with some obscure relation to gamma
For questions related to 'elementary' proofs in a technical sense, which has nothing to do with the difficulty of the argument or result. A typical example would be 'elementary' proofs of the Prime Nu…
Recreational mathematics or puzzles with serious mathematical content. Note that math contest problems are generally considered off-topic.
Stability theory, including global stability (in dynamical systems, where it can notably be used in combination with ds.dynamical-systems)
For questions on divisors and multiples, mainly but not exclusively of integers, and related and derived notions such as sums of divisors, perfect numbers and so on.
For questions that specifically ask for determining a closed form of equations, integrals etc.
the complexity class consisting of problems whose yes instances can be verified in polynomial time. NP stands for 'nondeterministic polynomial time '.
the study of varieties endowed with a Poisson structure, which is a certain kind of 2-tensor. This is closely related to symplectic geometry.