我一直收到此错误：file not found。我正在使用 Mac Pro 2019。
% % \documentclass[12pt]{article} \usepackage{graphicx}
\usepackage{amsmath} \usepackage{amssymb} \usepackage{amsfonts}
\usepackage{amsthm} \usepackage{longtable} \usepackage{multirow}
\usepackage{color} \usepackage{relsize} \input{epsf} % \input xy
\xyoption{all} % %\usepackage{showkeys} \usepackage{latexsym} % %
\newtheorem{lemma}{Lemma}[section]
\newtheorem{theorem}[lemma]{Theorem}
\newtheorem{proposition}[lemma]{Proposition}
\newtheorem{corollary}[lemma]{Corollary}
\newtheorem{conjecture}[lemma]{Conjecture}
\newtheorem{construction}[lemma]{Construction}
\newtheorem{example}[lemma]{Example}
\newtheorem{definition}[lemma]{Definition}
% Tweak the margins to match requirements. Seems to work OK.
\topmargin-0.5cm \footskip1cm \oddsidemargin0.5cm
\evensidemargin0cm \textwidth16cm \textheight21cm \vfuzz1pc
\hfuzz1pc
% Tweak chapter headings %\titleformat{\chapter}[display]
%{\sc\Huge\center}{\chaptername\,\,\thechapter}{0pt}{}{}
\newcommand{\id}{\mathrm{\underline{id}}} %\newcommand{\id}{\}
\renewcommand{\theequation}{\arabic{equation}}
% A 'Proof' environment. % This is done with the extra commands made
available from theorem %\theoremstyle{nonumberplain}
%\theoremheaderfont{\normalfont\itshape}
%\theorembodyfont{\normalfont} %\theoremseparator{.}
%\theoremsymbol{\ensuremath{\square}} %\newtheorem{pf}{Proof}
\renewcommand{\Gamma}{\varGamma} \renewcommand{\epsilon}{\varepsilon}
\renewcommand{\bar}{\overline} \renewcommand{\hat}{\widehat}
\renewcommand{\leq}{\leqslant} \renewcommand{\geq}{\geqslant}
%Extra things that are included for simplicity.
\newcommand{\Po}{\mathcal{P}} \newcommand{\R}{\mathbb{R}}
\newcommand{\Z}{\mathbb{Z}} \newcommand{\C}{\mathbb{C}} % %
\newcommand{\Sym}{\mathrm{Sym}}
\newcommand{\vt}{\mathrm{vert}} \newcommand{\conv}{\mathrm{conv}}
\newcommand{\Fix}{\mathrm{Fix}} \newcommand{\Span}{\mathrm{Span}}
\newcommand{\rank}{\mathrm{rank}}
\begin{document} BODY
\end{document}