Exercise · ZW-QUOTIENT-TOPOLOGY-005 · ★☆☆ Basic
Among all topologies on \(Y\) that make \(q:X\to Y\) continuous, the quotient topology is…
Choose one option.
A the coarsest (with the fewest open sets) B the finest (with the most open sets) C always the discrete one D always the trivial one
Show answer B. the finest (with the most open sets)
← Back to the question
Explanation It collects every \(V\) with \(q^{-1}(V)\) open, that is, as many open sets as the continuity of \(q\) allows; adding any other would break it.
The topology \(\mathcal{T}_q\) on \(Y\) determined by a surjective function \(q:X\to Y\) from a space \((X,\mathcal{T})\), whose open sets are the \(V\subseteq Y\) with \(q^{-1}(V)\) open in \(X\).
\[\mathcal{T}_q=\{V\subseteq Y:\ q^{-1}(V)\in\mathcal{T}\}\]
More practice problems: quotient topology ZW-QUOTIENT-TOPOLOGY-001 With X=\1,2,3,4\ with open sets ∅,\1\,\2\,\1,2\,\1,2,3\,X, Y=\a,b,c\ and q(1)=q(2)=a, q(3)=b, q(4)=…ZW-QUOTIENT-TOPOLOGY-002 With X=\1,2,3,4\ with open sets ∅,\1\,\2\,\1,2\,\1,2,3\,X, Y=\a,b,c\ and q(1)=q(2)=a, q(3)=b, q(4)=…ZW-QUOTIENT-TOPOLOGY-003 Let q:X→ Y be surjective and X a topological space. When is a set V⊆ Y open in the quotient topolog…ZW-QUOTIENT-TOPOLOGY-004 Identifying the endpoints of the interval [0,1] (that is, 0sim 1) with the quotient topology gives…ZW-QUOTIENT-TOPOLOGY-006 With X=\1,2,3,4\ with open sets ∅,\1\,\2\,\1,2\,\1,2,3\,X, Y=\a,b,c\ and q(1)=q(2)=a, q(3)=b, q(4)=…ZW-QUOTIENT-TOPOLOGY-007 Let X=\1,2,3,4\ have the discrete topology and q:X→\a,b\ be given by q(1)=q(2)=a, q(3)=q(4)=b. How…ZW-QUOTIENT-TOPOLOGY-008 Let X=\1,2,3\ have open sets ∅,\1\,\1,2\,X and q:X→\a,b\ with q(1)=a, q(2)=q(3)=b. How many open se…ZW-QUOTIENT-TOPOLOGY-009 Let X=\1,2,3\ have open sets ∅,\1\,\2\,\1,2\,X and q:X→\a,b\ with q(1)=q(2)=a, q(3)=b. What are the…