Disjoint Union Topology universal property as instance of final topology's universal property
114856
Universal property of initial topology
112050
Union of ascending chain of Topologies
118145
Mathematical symbol for disjoint set union
132868
Bijection between an infinite set and its union of a countably infinite set
120345
Topology induced by seminorms and initial topology
109374
Is the Discrete Topology on $X$ the Only One Containing All Infinite Subsets of $X$?
103717
Topological Property of the Set of Integers
151581
Prerequisite for Milnor Topology from a Differential Viewpoint
50880
Expressing $\Bbb N$ as an infinite union of disjoint infinite subsets.
59289
Nested Sequence of Topological Space and the Coherent Topology; Munkres Topology 35.9
149317
An open subset of $\mathbb{R}$ is an at-most-countable union of disjoint open intervals
135025
Axiomatization of a Topology using the Boundary
140168
What are the basis for co-countable and co-finite topologies
81423
Completeness and Topological Equivalence
111001
Does weak topology preserve topological vector space structure?
151950
Why is indiscrete topology unmetrizable?
21892
Any open subset of $\Bbb R$ is a countable union of disjoint open intervals