Topic
Urelement
About: Urelement is a research topic. Over the lifetime, 727 publications have been published within this topic receiving 13677 citations. The topic is also known as: ur-element.
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Papers
TL;DR: The theory of types as mentioned in this paper is a full-scale system for formalizing intuitionistic mathematics as developed, which allows proofs to appear as parts of propositions so that the propositions of the theory can express properties of proofs.
Abstract: Publisher Summary The theory of types is intended to be a full-scale system for formalizing intuitionistic mathematics as developed. The language of the theory is richer than the languages of traditional intuitionistic systems in permitting proofs to appear as parts of propositions so that the propositions of the theory can express properties of proofs. There are axioms for universes that link the generation of objects and types and play somewhat the same role for the present theory as does the replacement axiom for Zermelo–Fraenkel set theory. The present theory is based on a strongly impredicative axiom that there is a type of all types in symbols. This axiom has to be abandoned, however, after it has been shown to lead to a contraction. This chapter discusses Normalization theorem, which can be strengthened in two ways: it can be made to cover open terms and it can be proved that every reduction sequence starting from an arbitrary term leads to a unique normal term after a finite number of steps. The definition of the notion of convertibility and the proof that an arbitrary term is convertible can no longer be separated because the type symbols and the terms are generated simultaneously.
812 citations
Abstract: A utility theory is developed that parallels the von Neumann-Morgenstern utility theory, but makes no use of the assumption that preferences are complete (i.e., that any two alternatives are comparable).
633 citations
1 Jan 1990
TL;DR: The first part of the axiomatics of the Mizar system is presented in this paper. But it does not include the axioms of the Tarski Grothendieck set theory.
Abstract: This is the first part of the axiomatics of the Mizar system. It includes the axioms of the Tarski Grothendieck set theory. They are: the axiom stating that everything is a set, the extensionality axiom, the definitional axiom of the singleton, the definitional axiom of the pair, the definitional axiom of the union of a family of sets, the definitional axiom of the boolean (the power set) of a set, the regularity axiom, the definitional axiom of the ordered pair, the Tarski’s axiom A introduced in [1] (see also [2]), and the Fraenkel scheme. Also, the definition of equinumerosity is introduced.
514 citations
Book•
17 Nov 1982
TL;DR: The history of the Axiom of Choice can be traced back to the early 19th century, when Zermelo's axiomatization of set theory was discussed as mentioned in this paper.
Abstract: Prologue.- 1 The Prehistory of the Axiom of Choice.- 1.1 Introduction.- 1.2 The Origins of the Assumption.- 1.3 The Boundary between the Finite and the Infinite.- 1.4 Cantor's Legacy of Implicit Uses.- 1.5 The Well-Ordering Problem and the Continuum Hypothesis.- 1.6 The Reception of the Well-Ordering Problem.- 1.7 Implicit Uses by Future Critics.- 1.8 Italian Objections to Arbitrary Choices.- 1.9 Retrospect and Prospect.- 2 Zermelo and His Critics (1904-1908).- 2.1 Konig's "Refutation" of the Continuum Hypothesis.- 2.2 Zermelo's Proof of the Well-Ordering Theorem.- 2.3 French Constructivist Reaction.- 2.4 A Matter of Definitions: Richard, Poincare, and Frechet.- 2.5 The German Cantorians.- 2.6 Father and Son: Julius and Denes Konig.- 2.7 An English Debate.- 2.8 Peano: Logic vs. Zermelo's Axiom.- 2.9 Brouwer: A Voice in the Wilderness.- 2.10 Enthusiasm and Mistrust in America.- 2.11 Retrospect and Prospect.- 3 Zermelo's Axiom and Axiomatization in Transition (1908-1918).- 3.1 Zermelo's Reply to His Critics.- 3.2 Zermelo's Axiomatization of Set Theory.- 3.3 The Ambivalent Response to the Axiomatization.- 3.4 The Trichotomy of Cardinals and Other Equivalents.- 3.5 Steinitz and Algebraic Applications.- 3.6 A Smoldering Controversy.- 3.7 Hausdorff's Paradox.- 3.8 An Abortive Attempt to Prove the Axiom of Choice.- 3.9 Retrospect and Prospect.- 4 The Warsaw School, Widening Applications, Models of Set Theory (1918-1940).- 4.1 A Survey by Sierpi?ski.- 4.2 Finite, Infinite, and Mediate.- 4.3 Cardinal Equivalents.- 4.4 Zorn's Lemma and Related Principles.- 4.5 Widening Applications in Algebra.- 4.6 Convergence and Compactness in General Topology.- 4.7 Negations and Alternatives.- 4.8 The Axiom's Contribution to Logic.- 4.9 Shifting Axiomatizations for Set Theory.- 4.10 Consistency and Independence of the Axiom.- 4.11 Scepticism and Inquiry.- 4.12 Retrospect and Prospect.- Epilogue: After Godel.- 5.1 A Period of Stability: 1940-1963.- 5.2 Cohen's Legacy.- Conclusion.- Appendix 1 Five Letters on Set Theory.- Appendix 2 Deductive Relations Concerning the Axiom of Choice.- Journal Abbreviations Used in the Bibliography.- Index of Numbered Propositions.- General Index.
276 citations
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Performance Metrics
| Year | Papers |
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| 2025 | 5 |
| 2024 | 18 |
| 2023 | 7 |
| 2022 | 22 |
| 2021 | 3 |
| 2018 | 4 |