All Questions
Tagged with real-numbers set-theory
79
questions
1
vote
1
answer
95
views
Fields of intermediate cardinality (2)
Assuming the existence of a cardinal $\aleph_0 <\mathfrak{m} < 2^{\aleph_0}$, does it follow that there is a subfield of $\mathbb{R}$ of cardinality $\mathfrak{m}$ containing no algebraic ...
- 397k
2
votes
2
answers
178
views
Fields of intermediate cardinality
Assuming the existence of a cardinal $\aleph_0 <\mathfrak{m} < 2^{\aleph_0}$, does it follow that there is a subfield of $\mathbb{R}$ of cardinality $\mathfrak{m}$?
- 244k
1
vote
2
answers
422
views
Real numbers for beginners
I am thinking about the Wikipedia (I understand disputed) article about “definable real numbers”.
It begins to say that,
A real number $a$ is first-order definable in the language of set theory, ...
- 1,817
4
votes
1
answer
2k
views
Definable real numbers
Reading this Wikipedia page I found this definition:
A real number $a$ is first-order definable in the language of set
theory, without parameters, if there is a formula $\phi$ in the
language ...
- 397k