Combining Texts
Ideas for
'On the Question of Absolute Undecidability', 'First-order Logic, 2nd-order, Completeness' and 'works'
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11 ideas
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
10751
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Second-order logic needs the sets, and its consequence has epistemological problems [Rossberg]
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10757
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Henkin semantics has a second domain of predicates and relations (in upper case) [Rossberg]
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10759
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There are at least seven possible systems of semantics for second-order logic [Rossberg]
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5. Theory of Logic / B. Logical Consequence / 2. Types of Consequence
10753
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Logical consequence is intuitively semantic, and captured by model theory [Rossberg]
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5. Theory of Logic / B. Logical Consequence / 3. Deductive Consequence |-
10752
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Γ |- S says S can be deduced from Γ; Γ |= S says a good model for Γ makes S true [Rossberg]
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5. Theory of Logic / E. Structures of Logic / 1. Logical Form
10754
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In proof-theory, logical form is shown by the logical constants [Rossberg]
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5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
10756
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A model is a domain, and an interpretation assigning objects, predicates, relations etc. [Rossberg]
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5. Theory of Logic / J. Model Theory in Logic / 2. Isomorphisms
10758
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If models of a mathematical theory are all isomorphic, it is 'categorical', with essentially one model [Rossberg]
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5. Theory of Logic / K. Features of Logics / 4. Completeness
10761
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Completeness can always be achieved by cunning model-design [Rossberg]
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5. Theory of Logic / K. Features of Logics / 5. Incompleteness
17894
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We have no argument to show a statement is absolutely undecidable [Koellner]
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10755
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A deductive system is only incomplete with respect to a formal semantics [Rossberg]
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