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Worksheet 3.7 Homework 07

Instructions: Complete all the exercises below and submit your work via Gradescope by Monday April 13 at 10pm.

1.

Does mathematics contribute to human flourishing? State your opinion and explain why you hold it. (One-to-three paragraphs expected, but feel free to write more.)

2.

Let \(X\) be a space and let \(Y\) be a space that separates points. Show that the compact-open topology on \(\mathsf{Top}(X,Y)\) separates points.

3.

Let \(\mathbb{R}^{n\times n}\) denote the space of \(n\times n\) real matrices, which is naturally identified with the Euclidean space \(\mathbb{R}^{n^2}\text{.}\) Write \(\mathrm{O}(n)\subseteq\mathbb{R}^{n\times n}\) for the subspace of orthogonal matrices. Consider the function \(\mathbb{R}^n\times\mathbb{R}^{n\times n}\to\mathbb{R}^n\text{,}\) \((x,A)\mapsto Ax\text{.}\) Prove that the restriction of this map to \(\mathbb{R}^n\times\mathrm{O}(n)\to\mathbb{R}^n\) induces an embedding \(\mathrm{O}(n)\hookrightarrow\mathsf{Top}(\mathbb{R}^n,\mathbb{R}^n)\text{,}\) i.e., show that the curried map \(\mathrm{O}(n)\to\mathsf{Top}(\mathbb{R}^n,\mathbb{R}^n)\) is an injective continuous function that is a homeomorphism onto its image. (You will probably want to use the Fundamental Theorem of Topology; please be thorough and careful.)

4.

For \(a\ne 0\text{,}\) let \(f_a\colon [0,1]\to\mathbb{R}\) be given by \(f_a(x) := 1 - \frac{x}{a}\text{.}\) Define
\begin{equation*} \mathscr{F} := \{f_a\mid 0\lt a\le 1\}\subseteq\mathsf{Top}([0,1],\mathbb{R}). \end{equation*}
Prove or disprove: \(\mathscr{F}\) is compact in the compact-open topology.