# Monthly Archive: May 2020

Chapter 1 Riemann Integration §1A Review: Riemann Integral §1B Riemann Integral Is Not Good Enough Chapter 2 Measures §2A Outer Measure on R §2B Measurable Spaces and Functions §2C Measures and Their Properties §2D...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.16 Let $G$ be a group and $N \leq G$ a normal subgroup. Show that if $G = \langle S \rangle$,...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.15 Prove that a quotient of a divisible abelian group by any proper subgroup is also divisible. Deduce that $\mathbb{Q}/\mathbb{Z}$ is...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.14 Consider the additive quotient group $\mathbb{Q}/\mathbb{Z}$. (1) Show that every coset of $\mathbb{Z}$ in $\mathbb{Q}/\mathbb{Z}$ has exactly one representative $q...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.13 Let $G$ be the additive group of real numbers and $H$ the multiplicative group of complex numbers with absolute value...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.12 Let $G$ be the additive group of real numbers and $H$ the multiplicative group of complex numbers with absolute value...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.11 Let $F$ be a field and let $$G = \left\{ \begin{bmatrix} a & b \\ 0 & c \end{bmatrix} \...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.10 Let $\varphi : \mathbb{Z}/(8) \rightarrow \mathbb{Z}/(4)$ be defined by $\overline{a} \mapsto \overline{a}$. (Note that $\overline{a}$ means two different things here.)...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.9 Define $$\varphi : \mathbb{C}^\times \rightarrow \mathbb{R}^\times by a+bi \mapsto a^2 + b^2.$$ Prove that $\varphi$ is a homomorphism and find...

Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.1 Exercise 3.1.8 Let $\varphi : \mathbb{R}^\times \rightarrow \mathbb{R}^\times$ be given by $x \mapsto |x|$. Prove that $\varphi$ is a homomorphism and find...