Problème du cadre

In artificial intelligence, with implications for cognitive science, the frame problem describes an issue with using first-order logic (FOL) to express facts about a robot in the world. Representing the state of a robot with traditional FOL requires the use of many axioms that simply imply that things in the environment do not change arbitrarily. For example, Hayes describes a "block world" with rules about stacking blocks together. In a FOL system, additional axioms are required to make inferences about the environment (for example, that a block cannot change position unless it is physically moved). The frame problem is the problem of finding adequate collections of axioms for a viable description of a robot environment. John McCarthy and Patrick J. Hayes defined this problem in their 1969 article, Some Philosophical Problems from the Standpoint of Artificial Intelligence. In this paper, and many that came after, the formal mathematical problem was a starting point for more general discussions of the difficulty of knowledge representation for artificial intelligence. Issues such as how to provide rational default assumptions and what humans consider common sense in a virtual environment. In philosophy, the frame problem became more broadly construed in connection with the problem of limiting the beliefs that have to be updated in response to actions. In the logical context, actions are typically specified by what they change, with the implicit assumption that everything else (the frame) remains unchanged. The frame problem occurs even in very simple domains. A scenario with a door, which can be open or closed, and a light, which can be on or off, is statically represented by two propositions and . If these conditions can change, they are better represented by two predicates and that depend on time; such predicates are called fluents. A domain in which the door is closed and the light off at time 0, and the door opened at time 1, can be directly represented in logic by the following formulae: The first two formulae represent the initial situation; the third formula represents the effect of executing the action of opening the door at time 1.

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Concepts associés (7)

Problème du cadre

En informatique et philosophie, plus précisément en intelligence artificielle, le problème du cadre (frame problem en anglais) concerne la modélisation de l'effet des actions. Il s'agit d'énoncer la préservation du cadre : toutes les propriétés non modifiées par une action. Par exemple, si un robot pose une tasse sur une table, il faut non seulement spécifier que la tasse est désormais sur la table, mais aussi que la lumière reste allumée, que la table est toujours au même endroit, que le robot est toujours dans la même pièce etc.

Calcul des situations

The situation calculus is a logic formalism designed for representing and reasoning about dynamical domains. It was first introduced by John McCarthy in 1963. The main version of the situational calculus that is presented in this article is based on that introduced by Ray Reiter in 1991. It is followed by sections about McCarthy's 1986 version and a logic programming formulation. The situation calculus represents changing scenarios as a set of first-order logic formulae.

Fluent (artificial intelligence)

In artificial intelligence, a fluent is a condition that can change over time. In logical approaches to reasoning about actions, fluents can be represented in first-order logic by predicates having an argument that depends on time. For example, the condition "the box is on the table", if it can change over time, cannot be represented by ; a third argument is necessary to the predicate to specify the time: means that the box is on the table at time .