Skip to content
Draft
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions properties/P000052.md
Original file line number Diff line number Diff line change
Expand Up @@ -9,3 +9,8 @@ refs:
Every point is isolated, that is, $\{x\}$ is open for every point $x$.

See 3.2c of {{zb:1052.54001}}.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000054.md
Original file line number Diff line number Diff line change
Expand Up @@ -15,4 +15,5 @@ Defined on page 37 of {{zb:0386.54001}}.
----
#### Meta-properties

- This property is hereditary.
- This property is preserved by arbitrary disjoint unions.
5 changes: 5 additions & 0 deletions properties/P000057.md
Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,8 @@ refs:
The cardinality of the space is less than or equal to the cardinality of $\mathbb N$.

See sections 1.12-1.15 of {{zb:1052.54001}}.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000058.md
Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,8 @@ refs:
The cardinality of the space is less than the cardinality of $\mathbb R$.

See sections 1.12-1.15 of {{zb:1052.54001}}.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000059.md
Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,8 @@ refs:
The cardinality of the space is at most the cardinality of $\mathcal{P}(\mathbb R)$, the set of subsets of $\mathbb R$.

See sections 1.12-1.15 of {{zb:1052.54001}}.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000074.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,8 @@ refs:
A space that is {P5} and {P182}.

The notion was originally defined in section 10 of {{mr:206907}}, which is available at <https://www.jstor.org/stable/24901448>.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000078.md
Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,8 @@ refs:
The cardinality of the space is finite.

See sections 1.12-1.15 of {{zb:1052.54001}}.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000082.md
Original file line number Diff line number Diff line change
Expand Up @@ -13,4 +13,5 @@ Defined in exercise 7 of section 34 in {{zb:0951.54001}}.
----
#### Meta-properties

- This property is hereditary.
- The Kolmogorov quotient $\text{Kol}(X)$ is {P82} iff $X$ is {P144}.
5 changes: 5 additions & 0 deletions properties/P000094.md
Original file line number Diff line number Diff line change
Expand Up @@ -8,3 +8,8 @@ refs:
name: Locally finite space on Wikipedia
---
Every point has a finite neighborhood. Equivalently, the space has a basis of finite sets.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000097.md
Original file line number Diff line number Diff line change
Expand Up @@ -7,3 +7,8 @@ refs:
---

Homeomorphic to a subspace of $\mathbb R$ ({S25}).

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000100.md
Original file line number Diff line number Diff line change
Expand Up @@ -9,3 +9,8 @@ refs:
---

Every compact subset is closed.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000108.md
Original file line number Diff line number Diff line change
Expand Up @@ -24,4 +24,5 @@ For the equivalence of the conditions above, see {{mathse:4737011}}.
----
#### Meta-properties

- This property is hereditary.
- This property is preserved by arbitrary disjoint unions.
1 change: 1 addition & 0 deletions properties/P000112.md
Original file line number Diff line number Diff line change
Expand Up @@ -16,4 +16,5 @@ Equivalently, there is a continuous injective map from $X$ into some metrizable
----
#### Meta-properties

- This property is hereditary.
- This property is preserved by arbitrary disjoint unions.
5 changes: 5 additions & 0 deletions properties/P000113.md
Original file line number Diff line number Diff line change
Expand Up @@ -9,3 +9,8 @@ refs:
A space that is {P5} and {P110}.

See Definition 23.6 in {{zb:1052.54001}}.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000117.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,8 @@ A space with a $\sigma$-locally finite network.
A family $\mathcal N$ of subsets of $X$ is called a *network* if every open set is the union of a subfamily of $\mathcal N$; that is, for every open set $U$ and point $x\in U$ there is some $A\in\mathcal N$ with $x\in A\subseteq U$. The family $\mathcal N$ is *$\sigma$-locally finite* if it is a countable union of locally finite families.

See for example page 127 of {{zb:0684.54001}}.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000118.md
Original file line number Diff line number Diff line change
Expand Up @@ -15,4 +15,5 @@ See for example Definition 2.1 in {{doi:10.1016/j.topol.2015.05.085}}.
----
#### Meta-properties

- This property is hereditary.
- $X$ satisfies this property iff its Kolmogorov quotient $\text{Kol}(X)$ does.
5 changes: 5 additions & 0 deletions properties/P000129.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,8 @@ refs:
The only open sets are $\emptyset$ and $X$.

See 3.2d of {{zb:1052.54001}}.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000131.md
Original file line number Diff line number Diff line change
Expand Up @@ -19,4 +19,5 @@ Defined in 16E of {{zb:1052.54001}}.
----
#### Meta-properties

- This property is hereditary.
- $X$ satisfies this property iff its Kolmogorov quotient $\text{Kol}(X)$ does.
1 change: 1 addition & 0 deletions properties/P000132.md
Original file line number Diff line number Diff line change
Expand Up @@ -22,4 +22,5 @@ Note: A $G_\delta$ space is sometimes called a "perfect space" (Exercise 1.5.H(a
----
#### Meta-properties

- This property is hereditary.
- $X$ satisfies this property iff its Kolmogorov quotient $\text{Kol}(X)$ does.
5 changes: 5 additions & 0 deletions properties/P000137.md
Original file line number Diff line number Diff line change
Expand Up @@ -9,3 +9,8 @@ refs:
---

A space with no element, necessarily equal to {S163}.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000143.md
Original file line number Diff line number Diff line change
Expand Up @@ -13,3 +13,8 @@ refs:
A space $X$ such that for every compact Hausdorff space $K$ and every continuous map $f:K\to X$, the image $f(K)$ is closed in $X$.

Originally defined on p. 275 of {{doi:10.1090/S0002-9947-1969-0251719-4}}. See also <https://ncatlab.org/nlab/show/weakly+Hausdorff+topological+space>.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000144.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,4 +11,5 @@ Every point has a neighborhood that is {P121}.
----
#### Meta-properties

- This property is hereditary.
- $X$ is {P144} iff its Kolmogorov quotient $\text{Kol}(X)$ is {P82}.
1 change: 1 addition & 0 deletions properties/P000147.md
Original file line number Diff line number Diff line change
Expand Up @@ -17,4 +17,5 @@ Defined in {{doi:10.1016/0016-660X(72)90026-8}} with the additional assumption o
----
#### Meta-properties

- This property is hereditary.
- $X$ satisfies this property iff its Kolmogorov quotient $\text{Kol}(X)$ does.
5 changes: 5 additions & 0 deletions properties/P000163.md
Original file line number Diff line number Diff line change
Expand Up @@ -4,3 +4,8 @@ name: Cardinality $\leq\mathfrak c$
---

The cardinality of the space is less than or equal to the cardinality of $\mathbb R$.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000164.md
Original file line number Diff line number Diff line change
Expand Up @@ -26,3 +26,8 @@ Note: Some authors, for example {{doi:10.1007/978-1-4615-7819-2}}, refer to meas

(The existence of a measurable cardinal cannot be proven in ZFC.
So spaces whose construction does not depend on set-theoretic axioms beyond ZFC should never have this property marked as false.)

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000171.md
Original file line number Diff line number Diff line change
Expand Up @@ -26,3 +26,8 @@ reference to this weakening of {P3}.

Note: this property is not to be confused with other variants of k-Hausdorff (e.g. {P170}),
where k-closed is defined in terms of different notions of compactly generated space or k-space.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000177.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,8 @@ refs:
A space that is {P5} and {P117}.

The name "$\sigma$-space" was introduced by A. Okuyama (see {{doi:10.3792/pja/1195521153}}) to denote only the {P117} property. But most later papers, for example {{doi:10.1016/j.topol.2015.05.085}}, also include {P5} in this definition.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000178.md
Original file line number Diff line number Diff line change
Expand Up @@ -15,4 +15,5 @@ The notion was introduced in {{doi:10.1090/S0002-9939-1971-0276919-3}}.
----
#### Meta-properties

- This property is hereditary.
- The Kolmogorov quotient $\text{Kol}(X)$ is {P178} iff $X$ is {P11} and {P118}.
5 changes: 5 additions & 0 deletions properties/P000179.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,8 @@ refs:
A space that is {P5} and {P183}.

Originally defined in {{mr:206907}}, available at <https://www.jstor.org/stable/24901448>.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000180.md
Original file line number Diff line number Diff line change
Expand Up @@ -9,3 +9,8 @@ refs:
A space for which every subspace is {P26}.

Defined on page 182 of {{doi:10.1016/B978-0-444-50355-8.X5000-4}}.

----
#### Meta-properties

- This property is hereditary.
1 change: 1 addition & 0 deletions properties/P000183.md
Original file line number Diff line number Diff line change
Expand Up @@ -32,5 +32,6 @@ See {{mr:206907}}, available at <https://www.jstor.org/stable/24901448>.
---
### Meta-properties

- This property is hereditary.
- This property is preserved by countable products (see Corollary in {{mo:506308}}).

5 changes: 5 additions & 0 deletions properties/P000184.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,8 @@ refs:
Homeomorphic to a subspace of $\mathbb R^n$ for some finite $n$.

Per Theorems 1.1.2 and 1.11.4 of {{zb:0401.54029}}, this is equivalent to being {P27}, {P53}, and finite-dimensional, using any of the small inductive, large inductive, or covering dimensions by Theorem 1.7.7.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000185.md
Original file line number Diff line number Diff line change
Expand Up @@ -21,3 +21,8 @@ For proof of the equivalences and further characterizations, see section 13 of {

Defined as example #5 ("Partition Topology")
in {{zb:0386.54001}}.

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000220.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,8 @@ There exists an ultrametric inducing the topology of $X$.
A metric $d$ is called an *ultrametric* if it satisfies a property stronger than the triangle inequality, namely:

$\quad d(x, z) \leq \max(d(x, y), d(y, z)).$

----
#### Meta-properties

- This property is hereditary.
5 changes: 5 additions & 0 deletions properties/P000222.md
Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,8 @@ Equivalently, any of the following:
- A set $A\subseteq X$ is closed iff $A$ is finite or $A=X$.

- $X$ is *minimal $T_1$*, i.e., {P2} with no strictly coarser {P2} topology.

----
#### Meta-properties

- This property is hereditary.
Loading