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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/135558
Compactness and Löwenheim-Skolem theorems in extensions of first-order logic
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[en] Lindström’s theorem characterizes first-order logic as the most expressive among those that satisfy the countable Compactness and downward Löwenheim-Skolem theorems. Given the importance of this results in model theory, Lindström’s theorem justifies, to some extent, the privileged position of first-order logic in contemporary mathematics. Even though Lindström’s theorem gives a negative answer to the problem of finding a proper extension of first-order logic satisfying the same model-theoretical properties, the
study of these extensions has been of great importance during the second half of the
XX. century: logicians were trying to find systems that kept a balance between expressive
power and rich model-theoretical properties. The goal of this essay is to prove Lindström’s
theorem, along with its prerequisites, and to give weaker versions of the Compactness
and Löwenheim-Skolem theorems for the logic L ( Q 1 ) (first-order logic with the quantifier
"there exist uncountably many"), which we present as an example of extended logic with
good model-theoretical properties.
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Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2019, Director: Enrique Casanovas Ruiz-Fornells
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CASADO TELLETXEA, Ioar. Compactness and Löwenheim-Skolem theorems in extensions of first-order logic. [consulted: 10 of August of 2026]. Available at: https://hdl.handle.net/2445/135558