## Ramification and Causality (1997)

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Venue: | Artificial Intelligence |

Citations: | 154 - 22 self |

### BibTeX

@ARTICLE{Thielscher97ramificationand,

author = {Michael Thielscher},

title = {Ramification and Causality},

journal = {Artificial Intelligence},

year = {1997},

volume = {89},

pages = {317--364}

}

### Years of Citing Articles

### OpenURL

### Abstract

The ramification problem in the context of commonsense reasoning about actions and change names the challenge to accommodate actions whose execution causes indirect effects. Not being part of the respective action specification, such effects are consequences of general laws describing dependencies between components of the world description. We present a general approach to this problem which incorporates causality, formalized by directed relations between two single effects stating that, under specific circumstances, the occurrence of the first causes the second. Moreover, necessity of exploiting causal information in this way or a similar is argued by elaborating the limitations of common paradigms employed to handle ramifications, namely, the principle of categorization and the policy of minimal change. Our abstract solution is exemplarily integrated into a specific calculus based on the logic programming paradigm. To apper in: Artificial Intelligence Journal On leave from FG Inte...

### Citations

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Citation Context ...mir Lifschitz for this observation. 41 An approach which is considerably different from all methods discussed so far yet still related, is based on networks representing probabilistic causal theories =-=[34]-=-. These networks describe, in the first place, static dependencies among their components. As argued in [35, 36], however, the truth-values of one or more nodes may be re-set dynamically and, then, th... |

1851 |
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Citation Context ...tate transitions. Again, since stress shall lie on the ramification problem rather than on sophisticated methods of specifying the direct effects of actions, we employ a suitably simple, Strips-style =-=[9, 23]-=- notion of action specification. Each action law consists of • A condition C , which is a set of fluent literals all of which must be contained in the state at hand in order to apply the action law. •... |

1563 | Some philosophical problems from the standpoint of articial intelligence
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Citation Context ...ion, the nullary fluent light denotes the state of the light bulb as before. The state displayed in Figure 1 is then formalized as S = {on (s1), on (s2), light} . As opposed to the situation calculus =-=[32, 37]-=-, the fluent calculus employs structured state terms, each of which consists in a collection of all fluent literals that are true in the state being represented. To this end, fluent literals are reifi... |

975 | Negation as failure - Clark - 1978 |

851 |
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(Show Context)
Citation Context ...e predicate Caused is minimized given the direct effects of actions (like in (50)) and the laws of causality (each of which is of the form (49)). This is formally achieved by applying circumscription =-=[31]-=-. Hence, besides also leaving the effort of constructing the various causal relations to the designer, this method is grounded on the paradigm of minimal change as well. In fact, this work, too, appea... |

574 |
The frame problem in the situation calculus: a simple solution (sometimes) and a completeness result for goal regression
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(Show Context)
Citation Context ...ion, the nullary fluent light denotes the state of the light bulb as before. The state displayed in Figure 1 is then formalized as S = {on (s1), on (s2), light} . As opposed to the situation calculus =-=[32, 37]-=-, the fluent calculus employs structured state terms, each of which consists in a collection of all fluent literals that are true in the state being represented. To this end, fluent literals are reifi... |

395 | Representing action and change by logic programs
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(Show Context)
Citation Context ...m of action specifications as regards direct effects. Three recent, similarly high-level action semantics focus on sophisticated ways to formalize this aspect, namely, the Action Description Language =-=[13]-=-, the Ego-WorldSemantics [38], and the framework presented in [46]. These approaches are considered prime candidates for being enhanced by the concept of causal relationships. In case of the Action De... |

346 | Programs with common sense - McCarthy - 1958 |

264 |
Reasoning about action using a possible models approach
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Citation Context ...n minimal change successors. 16 Observation 11 is a consequence of a theorem stated and proved in [29], which essentially relates Definition 10 to the basic definition of the possible models approach =-=[48]-=-. Below, we provide a direct proof. 17 Notice that TC is obviously monotone, that is, Θ ⊆ Θ ′ always implies TC(Θ) ⊆ TC(Θ ′) (c.f. Definition 9). 18 A brief discussion on the nature of disjunctive cau... |

259 |
Nonmonotonic logic and temporal projection
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(Show Context)
Citation Context ...t the concept of causal relationships along with the notion of potential influence perfectly accounts for this distinction. Example 2 Consider the following adaption [1] of the Yale Shooting scenario =-=[18]-=-. We intend to hunt a turkey which is either alive or not (described via the fluent name alive ) and which is walking around or not (fluent name walking ). The domain constraint walking ⊃ alive restri... |

236 | Application of theorem proving to problem solving
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(Show Context)
Citation Context ...light (28) where the bar denoting negative fluent expressions is formally a unary function. It has first been argued in [19] that this representation technique avoids extra axioms (e.g., frame axioms =-=[32, 17]-=-) to encode the general law of persistence: The effects of actions can be modeled by manipulating terms like (28) through removal and addition of sub-terms. Then all sub-terms which are not affected b... |

229 | State constraints revisited
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- 1994
(Show Context)
Citation Context ...ion sequences. 3.3 Indirect Effects vs. Implicit Qualification Thus far we have seen how domain constraints give rise to additional, indirect effects of actions. However, it has been observed e.g. in =-=[15, 26]-=- that domain constraints might instead give rise to additional, implicit qualifications of actions. In the following, we illustrate that the concept of causal relationships along with the notion of po... |

188 | Embracing causality in specifying the indirect effects of actions
- Lin
- 1995
(Show Context)
Citation Context ...ential influences. Similar remarks apply to a recently developed integration of causality into the situation calculus-based framework presented in [26], also with the aim of handling indirect effects =-=[25]-=-. There, first-order formulas resembling causal relationships are used to define dependencies between effects and their indirect consequences. These formulas are of the form ∀s [ Φ(s) ∧ Caused(f1, v1,... |

144 | Reasoning about action I: A possible worlds approach
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(Show Context)
Citation Context ... information to prevent changes that are suggested syntactically by the mere domain constraints but contradict the intuition, was first observed in [15] in the context of the possible worlds approach =-=[14]-=-. There, indirect effects of actions are implicitly obtained by searching for successor states staying as close as possible to the original state while satisfying both the direct effects of the action... |

144 | Features and Fluents - Sandewall - 1995 |

137 | Nonmonotonic reasoning in the framework of the situation calculus
- Baker
- 1991
(Show Context)
Citation Context ...n the following, we illustrate that the concept of causal relationships along with the notion of potential influence perfectly accounts for this distinction. Example 2 Consider the following adaption =-=[1]-=- of the Yale Shooting scenario [18]. We intend to hunt a turkey which is either alive or not (described via the fluent name alive ) and which is walking around or not (fluent name walking ). The domai... |

134 | On the semantics of strips
- Lifschitz
- 1987
(Show Context)
Citation Context ...tate transitions. Again, since stress shall lie on the ramification problem rather than on sophisticated methods of specifying the direct effects of actions, we employ a suitably simple, Strips-style =-=[9, 23]-=- notion of action specification. Each action law consists of • A condition C , which is a set of fluent literals all of which must be contained in the state at hand in order to apply the action law. •... |

120 |
Features and Fluents. The Representation of Knowledge about Dynamical Systems
- Sandewall
- 1994
(Show Context)
Citation Context ... action name and a state. This can be used to describe actions with non-deterministic effect.6 6 Suppose, as an example, that a gun non-deterministically gets loaded or not when spinning its cylinder =-=[38]-=-. This may be formalized by the two action laws 〈{}, spin, {}〉 and 〈{loaded}, spin, {loaded}〉 . Both of them are applicable in the state {loaded} , which suggests two possible outcomes, viz. {loaded} ... |

116 | Building in equational theories - Plotkin - 1972 |

103 | Graphical models, causality, and intervention
- Pearl
- 1993
(Show Context)
Citation Context ...d so far yet still related, is based on networks representing probabilistic causal theories [34]. These networks describe, in the first place, static dependencies among their components. As argued in =-=[35, 36]-=-, however, the truth-values of one or more nodes may be re-set dynamically and, then, the values of all depending nodes need to be adjusted according to standard (Bayesian) rules of probability. This ... |

97 |
Frames in the space of situations
- Lifschitz
- 1990
(Show Context)
Citation Context ...roblem of how an adequate set of causal relationships can be automatically extracted from given domain constraints. There is, however, a crucial, well-known obstacle to be considered towards this end =-=[24]-=-: Despite the fact that the causal relationships in (5) are inspired by the underlying domain constraint sw1 ∧ sw2 ≡ light , this formula would give rise to additional, unintended causal relationships... |

93 |
Default Reasoning: Causal and Conditional Theories
- Geffner
- 1992
(Show Context)
Citation Context ... true, do(toggle1, s)) ] (50) The general axiom of persistence employed in this context is ∀a, s, f [ ¬∃v.Caused(f, v, do(a, s)) ⊃ (Holds(f, do(a, s)) ≡ Holds(f, s) ) ] 32 Moreover, a third approach, =-=[11, 12]-=-, which is based on a nonmonotonic theory of “conditional entailment,” is similar to [4, 29] in using expressions which resemble causal rules. A thorough and formal comparison between these three fram... |

91 |
A deductive solution for plan generation
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(Show Context)
Citation Context ...While the work reported in this article has been concentrated solely on the ramification problem, the fluent calculus—besides being closely related, in its basic form, to the Linear Connection Method =-=[2]-=- and reasoning about actions based on Linear Logic [16, 28]—has shown a wide range of applicability, e.g. regarding postdiction problems and non-deterministic actions [3], reasoning about counterfactu... |

90 |
A new deductive approach to planning
- Hölldobler, Schneeberger
- 1990
(Show Context)
Citation Context ...es of causal and evidential implications. 3 In the second part of the paper, Section 6, we integrate the concept of causal relationships into a particular action calculus, namely, the fluent calculus =-=[19, 20]-=-. While for the sake of simplicity states are described via a set of propositional constants in the first part (see Section 2), our calculus itself employs a more complex notion of fluent, which invol... |

72 | Reasoning about action ii: The qualification problem
- Ginsberg, Smith
- 1988
(Show Context)
Citation Context ...summarize what happens until someone, e.g. the reasoning agent himself, has the possibility to intervene by acting again (stopping the chair from falling, for instance). 3 The naming was suggested in =-=[15]-=-, inspired by [10]. The latter, however, was not devoted to the ramification problem in exactly the above sense, contrary to what is often claimed; rather, this thesis describes how to exploit logical... |

69 |
How to do things with worlds: On formalizing actions and plans
- Brewka, Hertzberg
- 1993
(Show Context)
Citation Context ...rature,22 the common fundamental 21 To see why, take S ∩ T1 = {c} , say, which entails the missing literal, a , given a ∨ c via (16). 22 E.g., frame vs. non-frame fluents [24]; relevant vs. dependent =-=[4]-=-; persistent vs. non-persistent [7]; or persistent , remanent and contingent fluents [6]. 19 assumption of categorization-based approaches is that an appropriate categorization always exists. With a s... |

67 |
Exploiting constraints in design synthesis. Thèse de Doctorat
- Finger
- 1987
(Show Context)
Citation Context ...pens until someone, e.g. the reasoning agent himself, has the possibility to intervene by acting again (stopping the chair from falling, for instance). 3 The naming was suggested in [15], inspired by =-=[10]-=-. The latter, however, was not devoted to the ramification problem in exactly the above sense, contrary to what is often claimed; rather, this thesis describes how to exploit logical consequences (cal... |

51 |
A theory of complete logic programs with equality
- Jaffar, Lassez, et al.
- 1984
(Show Context)
Citation Context ... literals. This requires an extended notion of the standard so-called unique name assumption. More precisely, we adopt the concept of unification completeness known from logic programming (see, e.g., =-=[21, 42, 47]-=-). Let E be an equational theory, that is, a set of universally quantified equations. Two terms s and t are said to be E-equal , written s =E t , iff s = t is entailed by E plus the standard axioms of... |

48 |
Causal theories for nonmonotonic reasoning
- Geffner
- 1990
(Show Context)
Citation Context ... true, do(toggle1, s)) ] (50) The general axiom of persistence employed in this context is ∀a, s, f [ ¬∃v.Caused(f, v, do(a, s)) ⊃ (Holds(f, do(a, s)) ≡ Holds(f, s) ) ] 32 Moreover, a third approach, =-=[11, 12]-=-, which is based on a nonmonotonic theory of “conditional entailment,” is similar to [4, 29] in using expressions which resemble causal rules. A thorough and formal comparison between these three fram... |

43 | Deriving properties of belief update from theories of action
- Val, Shoham
- 1993
(Show Context)
Citation Context ... To see why, take S ∩ T1 = {c} , say, which entails the missing literal, a , given a ∨ c via (16). 22 E.g., frame vs. non-frame fluents [24]; relevant vs. dependent [4]; persistent vs. non-persistent =-=[7]-=-; or persistent , remanent and contingent fluents [6]. 19 assumption of categorization-based approaches is that an appropriate categorization always exists. With a simple extension of our Electric Cir... |

35 | Computing change and specificity with equational logic programs
- Hölldobler, Thielscher
- 1995
(Show Context)
Citation Context ...es of causal and evidential implications. 3 In the second part of the paper, Section 6, we integrate the concept of causal relationships into a particular action calculus, namely, the fluent calculus =-=[19, 20]-=-. While for the sake of simplicity states are described via a set of propositional constants in the first part (see Section 2), our calculus itself employs a more complex notion of fluent, which invol... |

35 | Foundations of Equational Logic Programming, volume 353 - Hölldobler - 1989 |

31 | A probabilistic calculus of actions
- Pearl
- 1994
(Show Context)
Citation Context ...d so far yet still related, is based on networks representing probabilistic causal theories [34]. These networks describe, in the first place, static dependencies among their components. As argued in =-=[35, 36]-=-, however, the truth-values of one or more nodes may be re-set dynamically and, then, the values of all depending nodes need to be adjusted according to standard (Bayesian) rules of probability. This ... |

30 | Reasoning about action in first-order logic
- Elkan
- 1992
(Show Context)
Citation Context ... been established that take into account specific notions of causality, as does our method, to tackle the problem of unintended changes. The monotonic, situation calculus-based formalism developed in =-=[8]-=- supports specifications of indirect effects by means of complete descriptions of how the truth-value of a particular fluent might be caused to change. As an example, recall the basic Electric Circuit... |

28 |
Embracing causality in default reasoning
- Pearl
- 1988
(Show Context)
Citation Context ...able provided all changes are reasonable from the standpoint of causality. On the basis of these observations, a detailed comparison with related work can be found in the concluding discussion. 4 See =-=[33]-=- for a general discussion on the different natures of causal and evidential implications. 3 In the second part of the paper, Section 6, we integrate the concept of causal relationships into a particul... |

24 | Representing actions in equational logic programming
- Thielscher
- 1994
(Show Context)
Citation Context ...lized by the two action laws 〈{}, spin, {}〉 and 〈{loaded}, spin, {loaded}〉 . Both of them are applicable in the state {loaded} , which suggests two possible outcomes, viz. {loaded} and {loaded} . See =-=[45]-=- for details on how to represent and reason about non-deterministic actions on this basis. 5 Example 1 (continued) Suppose our Electric Circuit domain allows for two actions, namely, toggling either s... |

23 |
SLDNF-resolution with equality
- Shepherdson
- 1992
(Show Context)
Citation Context ... literals. This requires an extended notion of the standard so-called unique name assumption. More precisely, we adopt the concept of unification completeness known from logic programming (see, e.g., =-=[21, 42, 47]-=-). Let E be an equational theory, that is, a set of universally quantified equations. Two terms s and t are said to be E-equal , written s =E t , iff s = t is entailed by E plus the standard axioms of... |

22 | Actions with indirect effects
- Kartha, Lifschitz
- 1994
(Show Context)
Citation Context ... the paper, for the sake of simplicity. For our calculus, we introduce a richer notion of fluents. A fluent is now an n-place predicate with arguments chosen from a given set of objects (or entities) =-=[38, 22]-=-. This involves both a generalized concept of action laws and fluent formulas including quantifications. Yet by requiring finiteness of any underlying set of entities, we still guarantee decidability ... |

22 | Adventures in Associative-Commutative Unification - Lincoln, Christian - 1989 |

22 | Explicit and implicit indeterminism: Reasoning about uncertain and contradictory specifications of dynamic systems
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- 1996
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Citation Context ...hese approaches are considered prime candidates for being enhanced by the concept of causal relationships. In case of the Action Description Language, this should be based on the dialect developed in =-=[3]-=-, which includes the notion of non-determinism, here needed if more than a single successor state exists. The resulting extension would constitute an alternate to the variant of the Action Description... |

21 | Extending SLD-resolution to equational Horn clauses using E-unification - Gallier - 1989 |

21 | The logic of dynamic systems
- Thielscher
- 1995
(Show Context)
Citation Context ..., similarly high-level action semantics focus on sophisticated ways to formalize this aspect, namely, the Action Description Language [13], the Ego-WorldSemantics [38], and the framework presented in =-=[46]-=-. These approaches are considered prime candidates for being enhanced by the concept of causal relationships. In case of the Action Description Language, this should be based on the dialect developed ... |

20 | Reasoning about persistence: a theory of actions - Zhang, Foo - 1993 |

19 | An Analysis of Systematic Approaches to Reasoning about Actions and Change
- Thielscher
- 1994
(Show Context)
Citation Context ... actions based on Linear Logic [16, 28]—has shown a wide range of applicability, e.g. regarding postdiction problems and non-deterministic actions [3], reasoning about counterfactual action sequences =-=[44]-=-, or concurrent actions in conjunction with (locally) inconsistent specifications [3]. Thus, a main goal of future research consists in combining all these results, each of which focuses on a single o... |

19 |
Generating plans in linear logic I. Actions as proofs
- Masseron, Tollu, et al.
- 1993
(Show Context)
Citation Context ...ntrated solely on the ramification problem, the fluent calculus—besides being closely related, in its basic form, to the Linear Connection Method [2] and reasoning about actions based on Linear Logic =-=[16, 28]-=-—has shown a wide range of applicability, e.g. regarding postdiction problems and non-deterministic actions [3], reasoning about counterfactual action sequences [44], or concurrent actions in conjunct... |

18 | Representing concurrent actions and solving conflicts - Bornscheuer, Thielscher - 1996 |

18 | Opening the AC-unification race - Burckert, Herold, et al. - 1988 |

17 |
A temporal revision model for reasoning about world change
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- 1992
(Show Context)
Citation Context ...he missing literal, a , given a ∨ c via (16). 22 E.g., frame vs. non-frame fluents [24]; relevant vs. dependent [4]; persistent vs. non-persistent [7]; or persistent , remanent and contingent fluents =-=[6]-=-. 19 assumption of categorization-based approaches is that an appropriate categorization always exists. With a simple extension of our Electric Circuit domain, we will illustrate that the role of a fl... |

14 |
On the completeness of SLDENF-resolution
- Thielscher
- 1996
(Show Context)
Citation Context ... literals. This requires an extended notion of the standard so-called unique name assumption. More precisely, we adopt the concept of unification completeness known from logic programming (see, e.g., =-=[21, 42, 47]-=-). Let E be an equational theory, that is, a set of universally quantified equations. Two terms s and t are said to be E-equal , written s =E t , iff s = t is entailed by E plus the standard axioms of... |

13 | Systematic comparison of approaches to ramification using restricted minimzation of change
- Sandewall
- 1995
(Show Context)
Citation Context ...ve. For if we toggle either of sw1 or sw2 , then we prefer a change of light instead of a change of the other switch (as regards 23 The terms “primary” and “secondary,” respectively, were inspired by =-=[40]-=-. 20 light sw1 sw2 relay sw3 Figure 4: An extended electric circuit described by five fluents. The two possible states of the first switch are up ( sw 1 is true) and down ( sw1 is false). The current ... |