Segerberg's Dynamic Deontic Logic is a dynamic logic where among the set of all possible histories those fulfilling the norms are distinguished. An extension of this logic to obligations (respectively permissions and prohibitions) to do an action before a given deadline or during a given time interval is defined. These temporal constraints are defined by events which may have several occurrences (like the obligation to update a given file before midnight). Violations of these kinds of norms are defined in this logical framework.

The standard method to retrieve information can be formally defined as follows. To ask a query, one gives the properties of the entities to be retrieved, and the answer is the set of all the entities that satisfy the query. Another method, is to ask the overall information about a given entity, and the answer is the corresponding information. An example of the first kind of query is: ‘who are the persons who have had a car accident?’, an example of the second kind is: ‘what is the overall information about a given person?’. This latter method has deserved very few researches though it has great potential practical applications. However, it raises many non-trivial issues that are investigated here. The first one is to find a precise definition of the fact that a piece of information ‘is about’ a given entity. We propose a new formal definition of this notion of aboutness for query languages in first-order logic with function symbols, and the main properties that follow from this definition are presented. The second one is to define a bridge between this abstract semantic definition and automated deduction methods based on Resolution Principle. Deduction strategies are defined in this direction and it is proved that they are complete.

Abstract objects can be used to represent in a concise form answers that are communicated by telephone. We present a formal framework in first order logic in which are defined abtract answers, their lower bounds and their upper bounds. Algebraic formulas are given to efficiently compute the abstract answers from the abstraction of the predicates that occur in a given query. We also present a method to reduce the error caused by the abstraction process that has to be computed when users want to get an exact answer.

A domain-independent formula of first-order predicate calculus is a formula whose evaluation in a given interpretation does not change when we add a new constant to the interpretation domain. The formulas used to express queries, integrity constraints or deductive rules in the database field that have an intuitive meaning are domain independent. That is the reason why this class is of great interest in practice. Unfortunately, this class is not decidable, and the problem is to characterize new subclasses, as large as possible, which are decidable. A syntactic characterization of a class of formulas, the Evaluable formulas, which are proved to be domain independent are provided. This class is defined only for function-free formulas. It is also proved that the class of evaluable formulas contains the other classes of syntactically characterized domain-independent formulas usually found in the literature, namely, range-separable formulas and range-restricted formulas. Finally, it is shown that the expressive power of evaluable formulas is the same as that of domain-independent formulas. That is, each domain-independent formula admits an equivalent evaluable one. An important advantage of this characterization is that, to check if a formula is evaluable, it is not necessary to transform it to a normal form, as is the case for range-restricted formulas.