While historically the Fluent Calculus arose from approaches to the Frame Problem using non-classical, linear logics, an alternative is to view it as a development of the Situation Calculus with the aim of coping with the inferential aspect of the Frame Problem. Starting off from the concept of successor state axioms as a solution to the representational aspect, we show how by gradual improvement regarding the inferential aspect, but without losing the representational merits, one finally arrives at a novel version of the Fluent Calculus. We illustrate that under the provision that actions have no so-called open effects, any Situation Calculus specification can be transformed into an essentially equivalent Fluent Calculus specification. Our hope is that this alternative access to the Fluent Calculus both clarifies its role in relation to the most popular axiomatization paradigm and helps enhancing its acceptance.

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The paper describes a transition logic, TL, and a deductive formalism for it. It shows how various important aspects (such as ramification, qualification, specificity, simultaneity, indeterminism etc.) involved in planning (or in reasoning about action and causality for that matter) can be modelled in TL in a rather natural way. (The deductive formalism for) TL extends the linear connection method proposed earlier by the author by embedding the latter into classical logic, so that classical and resource-sensitive reasoning coexist within TL. The attraction of a logical and deductive approach to planning is emphasized and the state of automated deduction briefly described. 1 Introduction Artificial Intelligence (AI, or Intellectics [Bib92a]) aims at creating artificial (or computational [PMG98]) intelligence. Were there no natural intelligence, the sentence would be meaningless to us. Hence understanding natural intelligence by necessity has always been among the goals of Intel...

In formal theories for reasoning about actions, the qualification problem denotes the problem to account for the many conditions which, albeit being unlikely to occur, may prevent the successful execution of an action. By a simple counter-example in the spirit of the well-known Yale Shooting scenario, we show that the common straightforward approach of globally minimizing such abnormal disqualifications is inadequate as it lacks an appropriate notion of causality. To overcome this difficulty, we propose to incorporate causality by treating the proposition that an action is qualified as a fluent which is initially assumed away by default but otherwise potentially indirectly affected by the execution of actions. Our formal account of the qualification problem includes the proliferation of explanations for surprising disqualifications and also accommodates so-called miraculous disqualifications. We moreover sketch a version of the fluent calculus which involves default rules to address ...

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We show how a class of domains written in the Language E , a high level language for reasoning about actions, narratives and change, can be translated into the argumentation framework of Logic Programming without Negation as Failure (LPwNF). This translation enables us 1) to understand default persistence as captured by various temporal reasoning frameworks in a simple and natural way, by assigning higher priority to information about effects of later actions over effects of earlier actions; 2) to develop an argumentation-based computational model for this type of reasoning in logic programming goal-driven style.

low express the following: (i) Fluents which initially hold, or which have been initiated by an occurrence of an action, continue to hold until an occurrence of an action which terminates them. (ii) Fluents which do not initially hold, or which have been terminated by an occurrence of an action, continue not to hold until an occurrence of an action which initiates them. HoldsAt(f; t) / [InitialisedTrue(f) :Clipped(0; f; t)] (EC1) 1 :HoldsAt(f; t) / [InitialisedFalse(f) :Declipped(0; f; t)] (EC2) HoldsAt(f; t 2 ) / [Happens(a; t 1 ) Initiates(a; f; t 1 ) (EC3) t 1 ! t 2<F12.

. Agents situated in proactive environments are acting autonomously while the environment is evolving alongside, whether or not the agents carry out any particular actions. A formal framework for simulating and reasoning about this generalized kind of dynamic systems is proposed. The capabilities of the agents are modeled by a set of conditional rules in a temporal-logical format. The environment itself is modeled by an independent transition relation on the state space. The temporal language is given a declarative semantics. 1 Introduction To motivate what follows, we discuss some aspects of scenarios involving agents and their environment, both capable of changing the state of a#airs of the world. The environment in these scenarios is evolving freely, whether or not there is any action on the part of the agents. This seems realistic, many real-world scenarios are li e that. This contrasts with the scenario classes that have mainly been studied, where the environment is perce...

Successor state axioms are an optimal solution to the famous Frame Problem in reasoning about actions---but only as far as its representational aspect is concerned. We show how by gradually applying the principle of reification to these axioms, one can achieve gradual improvement regarding the inferential aspect without losing the representational merits. The resulting concept of state update axioms constitutes a novel version of what is known as the Fluent Calculus. We illustrate that under the provision that actions have no so-called open e#ects, any Situation Calculus specification can be transformed into an essentially equivalent Fluent Calculus specification, in which at the same time the representational and the inferential aspect of the Frame Problem are addressed.

When drawing conclusions about narratives, minimizing---to a reasonable extent---the occurrence of events is crucial. We argue that unguided minimization is insufficient in case events are causally connected, for it easily fails to distinguish unmotivated event occurrences from those that have a cause. Two solutions are offered, the first of which has the advantage of being straightforwardly realized but on the other hand has a restricted range of applicability. Our second solution overcomes these restrictions but requires two uncommon and novel features. First, event occurrences are identified as fluents, which allows to adapt a recent causality-oriented solution to the Ramification Problem so that if an event is caused by another event then the former is obtained as indirect effect of what caused the latter. Second, volitional actions and natural events which have no cause inside the reasoning context, are furnished with a special cause, namely, the reaching of the time-point at whic...