The tree equivalence of linear recursion schemes

In the paper, a complete system of transformation rules preserving the tree equivalence and a polynomial-time algorithm deciding the tree equivalence of linear polyadic recursion schemes are proposed. The algorithm is formulated as a sequential transformation process which brings together the schemes in question. In the last step, the tree equivalence problem for the given schemes is reduced to a global flow analysis problem which is solved by an efficient marking algorithm

Translucent Procedures, Abstraction without Opacity

This report introduces TRANSLUCENT PROCEDURES as a new mechanism for implementing behavioral abstractions. Like an ordinary procedure, a translucent procedure can be invoked, and thus provides an obvious way to capture a BEHAVIOR. Translucent procedures, like ordinary procedures, can be manipulated as first-class objects and combined using functional composition. But unlike ordinary procedures, translucent procedures have structure that can be examined in well-specified non-destructive ways, without invoking the procedure