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Fredrik Engström
University of Gothenburg
  1.  36
    Generalized Quantifiers in Dependence Logic.Fredrik Engström - 2012 - Journal of Logic, Language and Information 21 (3):299-324.
    We introduce generalized quantifiers, as defined in Tarskian semantics by Mostowski and Lindström, in logics whose semantics is based on teams instead of assignments, e.g., IF-logic and Dependence logic. Both the monotone and the non-monotone case is considered. It is argued that to handle quantifier scope dependencies of generalized quantifiers in a satisfying way the dependence atom in Dependence logic is not well suited and that the multivalued dependence atom is a better choice. This atom is in fact definably equivalent (...)
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  2.  20
    Invariance and Definability, with and Without Equality.Denis Bonnay & Fredrik Engström - 2018 - Notre Dame Journal of Formal Logic 59 (1):109-133.
    The dual character of invariance under transformations and definability by some operations has been used in classical works by, for example, Galois and Klein. Following Tarski, philosophers of logic have claimed that logical notions themselves could be characterized in terms of invariance. In this article, we generalize a correspondence due to Krasner between invariance under groups of permutations and definability in L∞∞ so as to cover the cases that are of interest in the logicality debates, getting McGee’s theorem about quantifiers (...)
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  3.  23
    Characterizing Quantifier Extensions of Dependence Logic.Fredrik Engström & Juha Kontinen - 2013 - Journal of Symbolic Logic 78 (1):307-316.
    We characterize the expressive power of extensions of Dependence Logic and Independence Logic by monotone generalized quanti ers in terms of quanti er extensions of existential second-order logic.
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  4.  68
    Transplendent Models: Expansions Omitting a Type.Fredrik Engström & Richard W. Kaye - 2012 - Notre Dame Journal of Formal Logic 53 (3):413-428.
    We expand the notion of resplendency to theories of the kind T + p", where T is a fi rst-order theory and p" expresses that the type p is omitted. We investigate two di erent formulations and prove necessary and sucient conditions for countable recursively saturated models of PA. Some of the results in this paper can be found in one of the author's doctoral thesis [3].
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  5.  46
    Reasoning About Truth in First-Order Logic.Claes Strannegård, Fredrik Engström, Abdul Rahim Nizamani & Lance Rips - 2013 - Journal of Logic, Language and Information 22 (1):115-137.
    First, we describe a psychological experiment in which the participants were asked to determine whether sentences of first-order logic were true or false in finite graphs. Second, we define two proof systems for reasoning about truth and falsity in first-order logic. These proof systems feature explicit models of cognitive resources such as declarative memory, procedural memory, working memory, and sensory memory. Third, we describe a computer program that is used to find the smallest proofs in the aforementioned proof systems when (...)
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  6.  13
    A Note on Standard Systems and Ultrafilters.Fredrik Engström - 2008 - Journal of Symbolic Logic 73 (3):824-830.
    Let (M, X) ⊨ ACA₀ be such that P X, the collection of all unbounded sets in X, admits a definable complete ultrafilter and let T be a theory extending first order arithmetic coded in X such that M thinks T is consistent. We prove that there is an end-extension N ⊨ T of M such that the subsets of M coded in N are precisely those in X. As a special case we get that any Scott set with a (...)
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  7.  1
    Notions of Resplendency for Logics Stronger Than First-Order Logic.Fredrik Engström - 2004 - Bulletin of Symbolic Logic 11 (2).
  8. Omitting Types in Expansions and Related Strong Saturation Properties.Fredrik Engström - 2003 - Bulletin of Symbolic Logic 10 (2).