Does infinity belongs to the set of all real numbers?
9969
Is infinity a real number?
137564
What exactly is meant by infinity?
9021
An infinite subset of a countable set is countable
114043
Prove the existence of a real number satisfying a property
156006
Cardinality of set containing all infinite subsets of $\mathbb{Q}$
65473
How can something finite become infinite?
157513
How can I prove that these sets are countable infinite?
78294
How does one denote the set of  all positive real numbers?
70940
Homework - set theory infinite union
44974
Infinite set and countable subsets
70196
Is there any well-ordered uncountable set of real numbers under the original ordering?
41262
Does the concept of infinity have any practical applications?
62348
One divided by Infinity?
111008
Show that $X $ is a infinite set ,it is connected in the finite complement topology?
58594
Is the empty set a subset of itself?
68976
Given real numbers: define integers?
20680
Does infinity exist in physical systems?