In this paper, we propose new notions related to unfolding semantics which clarify the relationship between procedural and fixpoint semantics of logic programs. We introduce 3 main new ideas:- the unfolding rule has an associativity property that ensures the adequacy of unfolding semantics

A general functorial framework for recursive definitions is presented in which simulation of a definition scheme by another one implies an ordering between the values defined by these schemes in an arbitrary model. Under mild conditions on the functor involved, the converse implication also holds: a model is constructed such that, if the values defined are ordered, there is a simulation between the definition schemes. The theory is illustrated by applications to context-free grammars, recursive procedures in imperative languages, and simulation and bisimulation of processes.

Our aim is to define a new fixpoint semantics which correctly models finite failure. In order to achieve this goal a new fixpoint operator is derived from a "suitable" concrete semantics by defining a Galois insertion modeling finite failure. The corresponding abstract fixpoint semantics

of approaches to the semantics of logic programs: that based on fixpoint theory. We do not attempt to cover much beyond this single area, which is already remarkably fruitful. We hope readers will see parallels with, and the divergences from the better known fixpoint treatments developed for other programming

to symbolically and finitely represent possibly infinite collections of provable goals. We define a fixpoint semantics based on a new operator in the style of TP working over constraints. An application of the fixpoint operator can be computed algorithmically. As sufficient conditions for termination, we show

First-order formulas allow natural descriptions of queries and rules. Van Gelder's alternating fixpoint semantics extends the well-founded semantics of normal logic programs to general logic programs with arbitrary first-order formulas in rule bodies. However, an implementation of general

. Therefore, in this article, we present a compressed, goal-independent collecting fixpoint semantics that contains the smallest set of terms that are sufficient to describe, by semantic closure, all possible rewritings. We prove soundness and completeness under ascertained conditions. The compactness

can be defined equivalently by a property of their false literals, as a model is stable iff the set of its false literals coincides with its greatest unfounded set. We then generalize the well-founded WP operator to disjunctive logic programs, give a fixpoint semantics for disjunctive stable models

is declarative in nature, and allows concurrent execution of long-running (possibly human-executed) activities. Modularity is in-corporated through the use of hierarchical clustering of activities. The GSM operational semantics is based on a variant of Event-Condition-Action (ECA) rules, which are used

of this extension is obtained by allowing oriented cycles, which had no meaning in usual polarized linear logic. We also free proof nets from additional constraints, leading up to a correctness criterion as straightforward as possible (since almost all proof structures are correct). Our system has a sound semantics