peek search
Reviews: Online Markov Decoding: Lower Bounds and Near-Optimal Approximation Algorithms
The authors propose three online inference methods, i.e., peek search, randomized peek search, and peek reset, for Markov chain models. They also use a proof framework to prove the competitive ratio for each method. The proof method first computes the lower bound of ON, so that gets the relationship between the ON and OPT. And then it uses the properties of geometric series to find an upper bound of competitive ratio. The authors also design a dynamic programming method to efficiently compute reward accumulation, and prove its complexity.
Peek Search: Near-Optimal Online Markov Decoding
Garg, Vikas K., Pichkhadze, Tamar
We resolve the fundamental problem of online decoding with ergodic Markov models. Specifically, we provide deterministic and randomized algorithms that are provably near-optimal under latency constraints with respect to the unconstrained offline optimal algorithm. Our algorithms admit efficient implementation via dynamic programs, and extend to (possibly adversarial) non-stationary or time-varying Markov settings as well. Moreover, we establish lower bounds in both deterministic and randomized settings subject to latency requirements, and prove that no online algorithm can perform significantly better than our algorithms.