You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A Survey of solution techniques for the partially observed Markov decision process 
Chapter Title:  ?(ei,a',u)+-~ ~f)i)(a')v(e)), ) 
1. Abstract of Cited Paper (BIB001):  We present three algorithms to solve the infinite horizon, expected discounted total reward partially observed Markov decision process POMDP. Each algorithm integrates a successive approximations algorithm for the POMDP due to A. Smallwood and E. Sondik with an appropriately generalized numerical technique that has been shown to reduce CPU time until convergence for the completely observed case. The first technique is reward revision. The second technique is reward revision integrated with modified policy iteration. The third is a standard extrapolation. A numerical study indicates the potentially significant computational value of these algorithms.

Literature Review:
where a' = 6(u)(ei) and where 6(u) ~ A is such that H~(~)u = Hu. Observe that the first operator requires HA times as many operations per iteration as does the second operator. Thus, approach 2, which combines reward revision and a modified policy iteration BIB001  appears to be more numerically attractive per iteration than does approach 1. This conjecture has been supported by numerical testing. Theoretical results associated with approach 2 are not nearly as well developed as those for approach 1; see BIB002 for details.