  This paper investigates the issues of combination and normalization of
interval-valued belief structures within the framework of Dempster-Shafer
theory of evidence. Existing approaches are reviewed and thoroughly analyzed.
The advantages and drawbacks of previous approach are presented. A new
optimality approach based on uncertainty measure is developed, where the
problem of combining interval-valued belief structures degenerates into
combining basic probability assignments. Numerical examples are provided to
illustrate the rationality of the proposed approach.
