Section: New Results
We have started a new collabarative project with Bielefeld Universität on an extension of Algebraic Dynamic Programming. We introduced a generic specification framework, called inverted coupled rewrite systems  , that can deal with optimization problems on strings, trees, and arc-annotated sequences. It is based on the following ideas: the solutions of combinatorial optimization problems are the inverse image of a term rewrite relation that reduces problem solutions to problem inputs. A tree grammar is used to further refine the search space, and optimization objectives are specified as interpretations of these terms. All these constituents provide a mathematically precise and complete problem specification, leading to concise yet translucent specifications of dynamic programming algorithms.