One-sided-error completeness for BPP
Determine whether every constant-cost randomized communication problem in the class BPP can be computed using a constant number of oracle queries to problems admitting one-sided-error (RP^0) constant-cost protocols.
References
All known problems in BPP can be solved with (1) queries to constant-cost problems with one-sided error (i.e. the class RP0). Is this always true? (See also [HH24]). We mentioned above that finding a complete problem (or hierarchy) could have answered many questions about BPP (depending on the properties of the complete problem itself); these two open problems are examples of that.
                — Constant-Cost Communication is not Reducible to k-Hamming Distance
                
                (2407.20204 - Fang et al., 29 Jul 2024) in Section: Constant-Cost Communication: the Story so Far and Farther