Lexical semantics is still in a rather early stage of development. This explains the reason why there are relatively few elaborated systems for representing its various aspects. A number of semantic aspects can be straightforwardly represented by means of feature-value pairs and by means of typed feature structures. Others, such as the Qualia Structure or the lexical semantics relations are more difficult to represent. The difficulty is twofold: (1) there is first the need to define appropriate models to represent the various levels of semantic information, including their associated possible inference systems and their properties (e.g., transitivity, monotonicity, etc.) and (2) there is the need to develop complex algorithms that allow for as efficient as possible treatments from these models. The first chapter of this section tackles the first point and the second one addresses some algorithmic problems.

“Introducing Lexlog” by J. Jayez, is a set of specifications for constructing explicit representations for lexical objects in restricted domains. Lexlog offers two types of functions: control functions to formalize representations and updatings on these representations in a controlled way, and expression functions to express different semantic operators and to tailor these operators with syntactic operators, for example, the trees of the Tree Adjoining Grammar framework. The discussion ends with a detailed presentation of the implementation in Prolog.

The last chapter, “Constraint propagation techniques for lexical semantics descriptions,” by Patrick Saint-Dizier, addresses the problem of the propagation in parse trees of large feature structures. The motivation is basically to avoid computations of intermediate results which later turn out to be useless.