Descriptive set theory

Inductive set

In descriptive set theory, an inductive set of real numbers (or more generally, an inductive subset of a Polish space) is one that can be defined as the least fixed point of a monotone operation definable by a positive Σ1n formula, for some natural number n, together with a real parameter. The inductive sets form a boldface pointclass; that is, they are closed under continuous preimages. In the Wadge hierarchy, they lie above the projective sets and below the sets in L(R). Assuming sufficient determinacy, the class of inductive sets has the scale property and thus the prewellordering property. The term having a number of different meanings.[1] According to: * Russell's definition, an inductive set is a nonempty partially ordered set in which every element has a successor. An example is the set of natural numbers N, where 0 is the first element, and the others are produced by adding 1 successively. * Roitman considers the same construction in a more abstract form: the elements are sets, 0 is replaced by the empty set, and the successor of every element y is the set y union {y}. In particular, every inductive set contains a sequence of the form. * For many other authors (e.g., Bourbaki), an inductive set is a partially ordered set in which every totally ordered subset has an upper bound, i.e., it is a set fulfilling the assumption of Zorn's lemma. (Wikipedia).

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Introducing Infinity | Set Theory, Section 3.1

In this video we define inductive sets, the natural numbers, the axiom of infinity, and the standard order relation on the natural numbers. My Twitter: https://twitter.com/KristapsBalodi3 Intro (0:00) Defining Natural Numbers as Sets (1:19) Definition of Inductive Sets (5:07) The Axiom o

From playlist Axiomatic Set Theory

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Set Theory (Part 7): Natural Numbers and Induction

Please feel free to leave comments/questions on the video and practice problems below! In this video, I discuss the von Neumann construction of the natural numbers and relate the idea of natural numbers to inductive sets. The axiom of infinity is also introduced here as one of the ZFC axi

From playlist Set Theory by Mathoma

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Set Theory 1.2 : Ordinals

In this video, I introduce the Von Neumann construction of the ordinals, including ones that are infinite/transfinite! Email : fematikaqna@gmail.com Subreddit : https://reddt.com/r/Fematika Code : https://github.com/Fematika/Animations Notes : None yet

From playlist Set Theory

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Higher Inductive Types - Peter Lumsdaine

Peter Lumsdaine Dalhousie University; Member, School of Mathematics October 1, 2012 For more videos, visit http://video.ias.edu

From playlist Mathematics

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Set Theory (Part 2): ZFC Axioms

Please feel free to leave comments/questions on the video and practice problems below! In this video, I introduce some common axioms in set theory using the Zermelo-Fraenkel w/ choice (ZFC) system. Five out of nine ZFC axioms are covered and the remaining four will be introduced in their

From playlist Set Theory by Mathoma

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Introduction to sets || Set theory Overview - Part 1

A set is the mathematical model for a collection of different things; a set contains elements or members, which can be mathematical objects of any kind: numbers, symbols, points in space, lines, other geometrical shapes, variables, or even other #sets. The #set with no element is the empty

From playlist Set Theory

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Introduction to sets || Set theory Overview - Part 2

A set is the mathematical model for a collection of different things; a set contains elements or members, which can be mathematical objects of any kind: numbers, symbols, points in space, lines, other geometrical shapes, variables, or even other #sets. The #set with no element is the empty

From playlist Set Theory

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Introduction to Sets and Set Notation

This video defines a set, special sets, and set notation.

From playlist Sets (Discrete Math)

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The perfect number of axioms | Axiomatic Set Theory, Section 1.1

In this video we introduce 6 of the axioms of ZFC set theory. My Twitter: https://twitter.com/KristapsBalodi3 Intro: (0:00) The Axiom of Existence: (2:39) The Axiom of Extensionality: (4:20) The Axiom Schema of Comprehension: (6:15) The Axiom of Pair (12:16) The Axiom of Union (15:15) T

From playlist Axiomatic Set Theory

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RA1.3. Peano Axioms and Induction

Real Analysis: We consider the Peano Axioms, which are used to define the natural numbers. Special attention is given to Mathematical Induction and the Well-Ordering Principle for N. (Included is an example of how to show a triple equivalence.)

From playlist Real Analysis

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Petra Hozzova - Automation of Induction in Saturation - IPAM at UCLA

Recorded 17 February 2023. Petra Hozzova of Technische Universität Wien, Institute of Logic and Computation, presents "Automation of Induction in Saturation" at IPAM's Machine Assisted Proofs Workshop. Abstract: Induction in saturation-based first-order theorem proving is a new exciting di

From playlist 2023 Machine Assisted Proofs Workshop

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Axiom of Regularity (Foundation) vs. Induction

Previous video on regularity: https://youtu.be/AqjctCRGxhw Errata: In 56:27 I say Regularity, but I meant to say Replacement. Text and links: https://gist.github.com/Nikolaj-K/bc9f67d685bcc7d1300372cfabceed9b

From playlist Logic

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Topology Without Tears - Video 4d - Writing Proofs in Mathematics

This is part (d) of the fourth video in a series of videos which supplement my online book "Topology Without Tears" which is available free of charge at www.topologywithouttears.net Video 4 focusses on the extremely important topic of writing proofs. This video is about Mathematical Induc

From playlist Topology Without Tears

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Well-Ordering and Induction: Part 1

This was recorded as supplemental material for Math 115AH at UCLA in the spring quarter of 2020. In this video, I prove the equivalence of the principle of mathematical induction and the well-ordering principle.

From playlist Well Ordering and Induction

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Introduction to University Mathematics - Oxford Mathematics 1st Year Student Lecture

This course is taken in the first two weeks of the first year of the Oxford Mathematics degree. It introduces the concepts and ways of mathematical thinking that students need in the years ahead. Much of the context will be familiar from high school but the way we think and write about i

From playlist Oxford Mathematics Student Lectures - Introduction to University Mathematics

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Regularity and non-standard models of arithmetic #PaCE1

Follow-up video: https://youtu.be/7HKnOOvssvs Discussed text, including all links: https://gist.github.com/Nikolaj-K/101c2712dc832dec4991bf568869abc8 Curt's call: https://youtu.be/V93GQaDtv8w Timestamps: 00:00:00 Introduction 00:02:55 Wittgenstein and predicates (optional) 00:11:12 Skolems

From playlist Logic

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Recursively Defined Sets - An Intro

Recursively defined sets are an important concept in mathematics, computer science, and other fields because they provide a framework for defining complex objects or structures in a simple, iterative way. By starting with a few basic objects and applying a set of rules repeatedly, we can g

From playlist All Things Recursive - with Math and CS Perspective

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Fundamentals of Mathematics - Lecture 15: Dedekind-Peano vs Peano Arithmetic

This is the class where we talk about the Extra Credit. course page: http://www.uvm.edu/~tdupuy/logic/Math52-Fall2017.html videography - Eric Melton - UVM

From playlist Fundamentals of Mathematics

Related pages

Descriptive set theory | Determinacy | L(R) | Real number | Wadge hierarchy | Polish space | Continuous function | Subset | Zorn's lemma