set-theory

Working internally in an elementary topos $\mathcal{E}$, let $X$ be an object of $\mathcal{E}$, $\mathcal{P}(X)$ its power object and consider a morphism $S: \mathcal{P}(X) \to \mathcal{P}(X)$ which ...

Previously: Ordinal numbers and basic set theory Ordinals as nim-heaps Nim always ends, even with infinite ordinals Infinite Nim as a coin-moving game Coin-moving games without the coins Previously we saw how to interpret the difficult-seeming ordinal as a particular ordering of the set of finite sequences of numbers, revealing what seemed like a scary monster as gentle and straightforward. Now w…

$\newcommand\of{\subseteq}\newcommand\N{\mathbb{N}}\newcommand\R{\mathbb{R}}\def\<#1>{\left\langle#1\right\rangle}\newcommand\Z{\mathbb{Z}}\newcommand\Q{\mathbb{Q}}\newcommand\ltomega{{{<}\omega}}\newcommand\unaryminus{-}\newcommand\intersect{\cap}\newcommand\union{\cup}\renewcommand\emptyset{\varnothing}$Let us explore the vast and densely populated expanses of the lattice of all sets of natural…
Previously: Ordinal numbers and basic set theory Ordinals as nim-heaps Nim always ends, even with infinite ordinals Infinite Nim as a coin-moving game In the previous article we saw how to interpret Nim heaps of up to beans as coins on a quarter-infinite array: The coin here represents a heap of beans. The heap can be reduced to any smaller number of beans. In the coin version of the game, this…

One reason I find set theory appealing as a foundation is that the axioms of ZFC feel clearly true based on the "iterative" concept of sets. More specifically, the axioms are true when the ...

Is it possible to kill a $\kappa$-Suslin tree by a ${<}\kappa$-strategically closed forcing? Note that the answer is negative for $\kappa$-strategic closure and (in particular) for ...
transfinite arithmetic, cardinal arithmetic, ordinal arithmetic prime field, p-adic integer, p-adic rational number, p-adic complex number arithmetic geometry, function field analogy The cardinal numbers (or just cardinals) constitute a generalisation of natural numbers to numbers of possibly infinite magnitudes. Specifically, cardinal numbers generalise the concept of ‘the number of …’. In parti…

This post is going to be about what infinite ordinal numbers are, and about is in particular. I had a brainwave a while back (18 months now, wow, I have definitely not been blogging enough) and suddenly understood much better than I did before. I have several related ideas here and I am going to try to write one blog post about each of them, instead of one gigantic blog post about all of them t…
Here I discuss definition of set, subset, proper subset, de Morgan’s law, Associative law, Cartesian product with theory and solve two maths problem. set theory with problem. problems with set theory. set theory problems and solutions. set theory sample problems. what is the problem with set theory. set theory problems and solutions pdf. group theory […]

research.ioSign up to keep scrolling
Create your feed subscriptions, save articles, keep scrolling.






