| 1. |
- Cantwell, John
(författare)
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Indicative conditionals : Factual or Epistemic
- 2008
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Ingår i: Studia Logica. - : Springer Science and Business Media LLC. - 0039-3215 .- 1572-8730. ; 88:1, s. 157-194
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Tidskriftsartikel (refereegranskat)abstract
- It is argued that indicative conditionals are best viewed as having truthconditions (and so they are in part factual) but that these truth conditions are ‘gappy’which leaves an explanatory gap that can only be filled by epistemic considerations (and soindicative conditionals are in part epistemic). This dual nature of indicative conditionalsgives reason to rethink the relationship between logic viewed as a descriptive discipline(focusing on semantics) and logic viewed as a discipline with a normative import (focusingon epistemic notions such as ‘reasoning’, ‘beliefs’ and ‘assumptions’). In particular, it isargued that the development of formal models for epistemic states can serve as a startingpoint for exploring logic when viewed as a normative discipline.
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| 2. |
- Eriksson Lundström, Jenny
(författare)
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Book Reviews
- 2009
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Ingår i: Studia Logica. - : Springer Science and Business Media LLC. - 0039-3215 .- 1572-8730. ; 93:1, s. 97-103
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Recension (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Fermé, Eduardo, et al.
(författare)
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Multiple Kernel Contraction
- 2003
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Ingår i: Studia Logica. - 0039-3215 .- 1572-8730. ; 73:2, s. 183-195
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the extension of AGM that allows change for a belief base by a set of sentences instead of a single sentence. In [FH94], Fuhrmann and Hansson presented an axiomatic for Multiple Contraction and a construction based on the AGM Partial Meet Contraction. We propose for their model another way to construct functions: Multiple Kernel Contraction, that is a modification of Kernel Contraction, proposed by Hansson [Han94] to construct classical AGM contractions and belief base contractions. This construction works out the unsolved problem pointed out by Hansson in [Han99, pp. 369].
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| 4. |
- Gabbay, Dov, et al.
(författare)
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Annotation Theories over Finite Graphs
- 2009
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Ingår i: Studia Logica. - : Springer. - 0039-3215 .- 1572-8730. ; 93:2-3, s. 147-180
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Tidskriftsartikel (refereegranskat)abstract
- In the current paper we consider theories with vocabulary containing a number of binary and unary relation symbols. Binary relation symbols represent labeled edges of a graph and unary relations represent unique annotations of the graph’s nodes. Such theories, which we call annotation theories, can be used in many applications, including the formalization of argumentation, approximate reasoning, semantics of logic programs, graph coloring, etc. We address a number of problems related to annotation theories over finite models, including satisfiability, querying problem, specification of preferred models and model checking problem. We show that most of considered problems are NPTime- or co-NPTime-complete. In order to reduce the complexity for particular theories, we use second-order quantifier elimination. To our best knowledge none of existing methods works in the case of annotation theories. We then provide a new second-order quantifier elimination method for stratified theories, which is successful in the considered cases. The new result subsumes many other results, including those of [2, 28, 21].
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| 5. |
- Gabbay, D.M., et al.
(författare)
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Second-order quantifier elimination in higher-order contexts with applications to the semantical analysis of conditionals
- 2007
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Ingår i: Studia Logica. - : Springer. - 0039-3215 .- 1572-8730. ; 87:1, s. 37-50
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Tidskriftsartikel (refereegranskat)abstract
- Second-order quantifier elimination in the context of classical logic emerged as a powerful technique in many applications, including the correspondence theory, relational databases, deductive and knowledge databases, knowledge representation, commonsense reasoning and approximate reasoning. In the current paper we first generalize the result of Nonnengart and Szalas [17] by allowing second-order variables to appear within higher-order contexts. Then we focus on a semantical analysis of conditionals, using the introduced technique and Gabbay's semantics provided in [10] and substantially using a third-order accessibility relation. The analysis is done via finding correspondences between axioms involving conditionals and properties of the underlying third-order relation. © 2007 Springer Science+Business Media B.V.
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| 6. |
- Hansson, Sven Ove
(författare)
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A Characterization of Probability-based Dichotomous Belief Revision
- 2022
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Ingår i: Studia Logica. - : Springer. - 0039-3215 .- 1572-8730. ; 110:2, s. 511-543
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates the properties of multistate top revision, a dichotomous (AGM-style) model of belief revision that is based on an underlying model of probability revision. A proposition is included in the belief set if and only if its probability is either 1 or infinitesimally close to 1. Infinitesimal probabilities are used to keep track of propositions that are currently considered to have negligible probability, so that they are available if future information makes them more plausible. Multistate top revision satisfies a slightly modified version of the set of basic and supplementary AGM postulates, except the inclusion and success postulates. This result shows that hyperreal probabilities can provide us with efficient tools for overcoming the well known difficulties in combining dichotomous and probabilistic models of belief change.
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| 7. |
- Hansson, Sven Ove
(författare)
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A Monoselective Presentation of AGM Revision
- 2015
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Ingår i: Studia Logica. - Royal Inst Technol KTH, Stockholm, Sweden. : Springer Science and Business Media LLC. - 0039-3215 .- 1572-8730. ; 103:5, s. 1019-1033
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Tidskriftsartikel (refereegranskat)abstract
- A new equivalent presentation of AGM revision is introduced, in which a preference-based choice function directly selects one among the potential outcomes of the operation. This model differs from the usual presentations of AGM revision in which the choice function instead delivers a collection of sets whose intersection is the outcome. The new presentation confirms the versatility of AGM revision, but it also lends credibility to the more general model of direct choice among outcomes (descriptor revision) of which AGM revision is shown here to be a special case.
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| 8. |
- Hansson, Sven Ove
(författare)
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A new representation theorem for contranegative deontic logic
- 2004
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Ingår i: Studia Logica. - 0039-3215 .- 1572-8730. ; 77, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The logic of an ought operator O is contranegative with respect to an underlying preference relation if it satisfies the property Op & (¬p)(¬q) Oq. Here the condition that is interpolative ((p (pq) q) (q (pq) p)) is shown to be necessary and sufficient for all -contranegative preference relations to satisfy the plausible deontic postulates agglomeration (Op & OqO(p&q)) and disjunctive division (O(p&q) Op Oq).
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| 9. |
- Hansson, Sven Ove
(författare)
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Back to Basics : Belief Revision Through Direct Selection
- 2019
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Ingår i: Studia Logica. - : SPRINGER. - 0039-3215 .- 1572-8730. ; 107:5, s. 887-915
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Tidskriftsartikel (refereegranskat)abstract
- Traditionally, belief change is modelled as the construction of a belief set that satisfies a success condition. The success condition is usually that a specified sentence should be believed (revision) or not believed (contraction). Furthermore, most models of belief change employ a select-and-intersect strategy. This means that a selection is made among primary objects that satisfy the success condition, and the intersection of the selected objects is taken as outcome of the operation. However, the select-and-intersect method is difficult to justify, in particular since the primary objects (usually possible worlds or remainders) are not themselves plausible outcome candidates. Some of the most controversial features of belief change theory, such as recovery and the impossibility of Ramsey test conditionals, are closely connected with the select-and-intersect method. It is proposed that a selection mechanism should instead operate directly on the potential outcomes, and select only one of them. In this way many of the problems that are associated with the select-and-intersect method can be avoided. This model is simpler than previous models in the important Ockhamist sense of doing away with intermediate, cognitively inaccessible objects. However, the role of simplicity as a choice criterion in the direct selection among potential outcomes is left as an open issue.
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| 10. |
- Hansson, Sven Ove
(författare)
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Bootstrap Contraction
- 2013
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Ingår i: Studia Logica. - : Springer Science and Business Media LLC. - 0039-3215 .- 1572-8730. ; 101:5, s. 1013-1029
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Tidskriftsartikel (refereegranskat)abstract
- We can often specify how we would contract by a certain sentence by saying that this contraction would coincide with some other contraction that we know how to perform. We can for instance clarify that our contraction by p&q would coincide with our contraction by p, or by q, or by {p, q}. In a framework where the set of potential outcomes is known, some contractions are "self-evident" in the sense that there is only one serious candidate that can be the outcome of such a contraction. Contraction by a specific contractee (sentence or set of sentences to be contracted) is bootstrapped if it is specified by saying that it coincides with some such self-evident contraction. For a wide range of (multiple) contraction operators, contractions by any contractee can be bootstrapped. This means that the selection mechanism (selection function, incision function, etc.) can be replaced by a function called a bootstrapping selector that assigns to each contractee some "self-evident" contractee that yields the same outcome. With bootstrapping we can eliminate traditional extralogical components in contraction (e.g., selection functions) and replace them by bootstrapping selectors that reflect more closely the ways in which we actually reason and argue about belief contraction.
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