Ordering constraints on trees -- Graph grammars and tree transducers -- Type Preorders -- Compilative constructive negation in constraint logic programs -- A new linear algorithm for Modular Decomposition -- A CPS-translation of the ??-calculus -- A lower bound on the growth of functions computed by tree transductions -- On the decidability of model checking for several ?-calculi and Petri nets -- Generalizations of the periodicity theorem of Fine and Wilf -- Probabilistic domains -- Some results on top-context-free tree languages -- On higher order recursive program schemes -- Graphs and decidable transductions based on edge constraints -- Nondeterministic automata with concurrency relations and domains -- Algebraic and combinatorial properties of simple, coloured walks -- Probabilistic analysis of an election algorithm in a tree -- On the first-order equivalence of call-by-name and call-by-value -- On the modularity of confluence of constructor-sharing term rewriting systems -- Global program analysis in constraint form -- On projective and separable properties -- A rank hierarchy for deterministic tree-walking transducers -- Superposition in picture languages -- A grammar-based data-flow analysis to stop deforestation.

This volume contains the papers selected for presentation at the 19th Colloquium on Trees in Algebra and Programming (CAAP '94), which was held jointly with the fifth European Symposium on Programming (ESOP '94) in Edinburgh in April 1994. Originally this colloquium series was devoted to the algebraic and combinatorial properties of trees, and their role in various fields of computer science. Taking into account the evolution of computer science, CAAP '94 focuses on logical, algebraic and combinatorial properties of discrete structures (strings, trees, graphs, etc.); the topics also include applications to computer science provided that algebraic or syntactic methods are involved. The volume contains 21 papers selected from 51 submissions as well as two invited papers.