Dec 3, 2025 · There is something I don't understand about the proof that non-empty perfect sets are uncountable. The same proof is present in Rudin's Principles of Mathematical Analysis. Do …

We can use the above theorem to show that $\mathbb R$ is in fact with bijection with $\mathcal P (\mathbb N)$, and therefore $\mathbb R$ is not countable. Since the above shows that …

My friend and I were discussing infinity and stuff about it and ran into some disagreements regarding countable and uncountable infinity. As far as I understand, the list of all natural …

I'm trying to show that the interval $(0,1)$ is uncountable and I want to verify that my proof is correct My solution: Suppose by way of contradiction that $(0, 1)$ is countable. Then we can …

May 16, 2024 · We know the interval $ [0, 1]$ is uncountable. You can think of the binary expansions of all numbers in $ [0, 1]$. This will give you an uncountable collection of sequences.

Sep 13, 2018 · In set theory, when we talk about the cardinality of a set we have notions of finite, countable and uncountably infinite sets. Main Question Let's talk about the dimension of a …

Nov 5, 2023 · Whether the uncountable sum of zeros is zero or not simply depends on the definition of uncountable sum you're using. After all, concepts in mathematics require formal …

A set $A$ is countable if $A\approx\mathbb {N}$, and uncountable if it is neither finite nor countably infinite.

Jun 4, 2023 · And since $\aleph_0$ is the cardinality of any countable set, this means that this power set must be uncountable. Some other ways to construct infinite sets are simply to add …

Apr 20, 2025 · Well no, removing one element from an uncountable set still leaves an uncountable set. Indeed, removing a countable number of elements from an uncountable set …