On the power of bounded concurrency II: The pushdown automata level -- Trees everywhere -- Combinatory forms for equational programming: Instances, unification and narrowing -- Graphical versus logical specifications -- More efficient bottom-up tree pattern matching -- On the regular structure of prefix rewriting -- A unified approach for showing language containment and equivalence between various types of ?-automata -- Unitary monoid with two generators: An algorithmic point of view -- Coherence of subsumption -- Petri nets as models of linear logic -- Towards the unification of models for concurrency -- A markovian concurrency measure -- Graph matching in operational semantics and typing -- ML typability is dexptime-complete -- Testing for inductiue (co)-reducibility -- Probabilistic analysis of some distributed algorithms -- Infinite values in hierarchical imperative types -- Equivalence of finite-valued bottom-up finite state tree transducers is decidable.

This volume contains the proceedings of the Fifteenth Colloquium on Trees in Algebra and Programming. The papers selected present new research results and cover the following topics: - Logical, algebraic and combinatorial properties of discrete structures (strings, trees, graphs, etc.), including the theory of formal languages considered as that of sets of discrete structures and the theory of rewriting systems over these objects. - Application of discrete structures in computer science, including syntax and semantics of programming languages, operational semantics, logic programming, algorithms and data structures, complexity of algorithms and implementation aspects, proof techniques for nonnumerical algorithms, formal specifications, and visualization of trees and graphs.