In computability theory, a set P of functions
is said to be Mučnik-reducible to another set Q of functions
when for every function g in Q, there exists a function f in P which is Turing-reducible to g.[1] Unlike most reducibility relations in computability, Mučnik reducibility is not defined between functions
These sets are called "mass problems" and can be viewed as problems with more than one solution.
Informally, P is Mučnik-reducible to Q when any solution of Q can be used to compute some solution of P.[2] This mathematical logic-related article is a stub.