\documentclass[12pt]{amsart}[1996/10/24] \NeedsTeXFormat{LaTeX2e} \DeclareOption*{\PassOptionsToClass{\CurrentOption}{amsart}} \ProcessOptions\relax \usepackage{amsmath,amscd,stmaryrd,mathrsfs,amssymb} %If does not work, remove stmaryrd, change \owedge into \owedge \renewcommand {\baselinestretch}{1.0} %% \topmargin 0pt %%\advance \topmargin by -\headheight %%\advance \topmargin by -\headsep \textheight 8.8in \parskip=.1in %%\oddsidemargin .25in %%\evensidemargin \oddsidemargin %%\marginparwidth 0.5in %%\textwidth 6.0in \newtheorem{theorem}[equation]{Theorem} \newtheorem{lemma}[equation]{Lemma} \newtheorem{corollary}[equation]{Corollary} \newtheorem{definition}[equation]{Definition} \newtheorem{example}[equation]{Example} \newtheorem{remark}[equation]{Remark} \newtheorem{conjecture}[equation]{Conjecture} \numberwithin{equation}{section} \newcommand{\Vol}{\operatorname{Vol}} \newcommand{\ii}{\sqrt{-1}} \newcommand{\Hess}{\operatorname{Hess}} \newcommand{\Rm}{\operatorname{Rm}} \newcommand{\Lip}{\operatorname{Lip}} \newcommand{\proj}{\operatorname{proj}} \newcommand{\Ric}{\operatorname{Ric}} \newcommand{\aint}{-\!\!\!\!\!\!\int} \newcommand{\Diam}{\operatorname{Diam}} \newcommand{\dGH}{\stackrel{d_{GH}}{\longrightarrow}} \newcommand{\be}{\begin{equation}} \newcommand{\ee}{\end{equation}} \begin{document} \thispagestyle{empty} \begin{center} {\sc California State University, Long Beach \\ Department of Mathematics\\ Complex Analysis Comprehensive Examination\\ February 8, 2025 } \end{center} \noindent{\bf Do three problems from each part, for a total of six problems. Circle the problems you want to be graded.} \begin{center} {\bf PART A} \end{center} \noindent {\bf Problem 1}. Compute \[ \int_{-\infty}^\infty \frac{x^2}{1+2x^2+x^4} dx. \] \noindent {\bf Problem 2}. Find the Laurent series for $f(z)=\frac{1}{z(z-1)(z-2)}$ around $z_0=1$. \noindent {\bf Problem 3}. \begin{enumerate} \item Compute \[ \int_\gamma \frac{z}{(z-1)(z-2)(z-3)}dz \] where $\gamma$ is the circle $|z|=4$. \item Compute \[ \int_\gamma \frac{z^8}{(z-1)(z-2)...(z-10)}dz \] where $\gamma$ is the circle $|z|=11$. \end{enumerate} \noindent {\bf Problem 4}. Consider the polynomial $f(z)=z^4+5z+1$. Find out the number of zeros of $f$ in the annulus $\{z\in \mathbb{C}: 1<|z|<2\}$. \noindent {\bf Problem 5}. Find the Residue at each pole for the function $f(z)=\frac{1}{z^2 \sin z}$ and evaluate the integral $\int_{\mathbb{C}}f(z) dz$ where $\mathbb{C}$ is the circle $|z|=10$ traversed once in the counterclockwise direction. \pagestyle{empty} \[\] \[\] \begin{center} {\bf PART B} \end{center} \noindent {\bf Problem 6}. Assume $f$ and $g$ are analytic on $\mathbb C$, and assume there are infinitely many $q$ such that $|q|\leq 1$ and $f(q)=g(q)$. Prove that $f=g$ everywhere. \noindent {\bf Problem 7}. Assume $f$ is entire. Prove that if $\underset{z\rightarrow \infty}{ \lim}f(z)=0$, then $f(z)=0$ for any $z$. \noindent {\bf Problem 8}. \begin{enumerate} \item State the fundamental theorem of algebra. \item Prove the fundamental theorem of algebra using the Liouville's theorem. \end{enumerate} \noindent {\bf Problem 9}. Assume $f$ is analytic on ${\mathbb C}$, and there is $M>0$ so that $|f(z)|\leq M(1+\sqrt{|z|})$ for all $z$. Prove that $f$ is a constant. \noindent {\bf Problem 10}. \begin{enumerate} \item State and prove Morera's Theorem. \item Give the statement of a claim or theorem whose proof relies on Morera’s Theorem. (You need not provide proof.) \end{enumerate} \end{document}