Tikhonov's theorem or Tychonoff's theorem may refer to any of several mathematical theorems named after the Russian mathematician Andrey Tikhonov:
Tychonoff's theorem, the product of any collection of compact topological spaces is compact Tikhonov's fixed point theorem, concerning fixed points of continuous mappings on compact subsets of certain topological vector spaces Tikhonov's theorem (dynamical systems), concerning limiting behaviour of solutions of systems of differential equations applicable to (among other things) chemistry
See also Andrey Tikhonov (mathematician) Tikhonov distribution Tikhonov regularization Tychonoff space