diff --git a/.gitignore b/.gitignore
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--- /dev/null
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+## Core latex/pdflatex auxiliary files:
+*.aux
+*.lof
+*.log
+*.lot
+*.fls
+*.out
+*.toc
+*.fmt
+*.fot
+*.cb
+*.cb2
+.*.lb
+
+## Intermediate documents:
+*.dvi
+*.xdv
+*-converted-to.*
+# these rules might exclude image files for figures etc.
+# *.ps
+# *.eps
+# *.pdf
+
+## Generated if empty string is given at "Please type another file name for output:"
+.pdf
+
+## Bibliography auxiliary files (bibtex/biblatex/biber):
+*.bbl
+*.bcf
+*.blg
+*-blx.aux
+*-blx.bib
+*.run.xml
+
+## Build tool auxiliary files:
+*.fdb_latexmk
+*.synctex
+*.synctex(busy)
+*.synctex.gz
+*.synctex.gz(busy)
+*.pdfsync
+
+## Build tool directories for auxiliary files
+# latexrun
+latex.out/
+
+## Auxiliary and intermediate files from other packages:
+# algorithms
+*.alg
+*.loa
+
+# achemso
+acs-*.bib
+
+# amsthm
+*.thm
+
+# beamer
+*.nav
+*.pre
+*.snm
+*.vrb
+
+# changes
+*.soc
+
+# comment
+*.cut
+
+# cprotect
+*.cpt
+
+# elsarticle (documentclass of Elsevier journals)
+*.spl
+
+# endnotes
+*.ent
+
+# fixme
+*.lox
+
+# feynmf/feynmp
+*.mf
+*.mp
+*.t[1-9]
+*.t[1-9][0-9]
+*.tfm
+
+#(r)(e)ledmac/(r)(e)ledpar
+*.end
+*.?end
+*.[1-9]
+*.[1-9][0-9]
+*.[1-9][0-9][0-9]
+*.[1-9]R
+*.[1-9][0-9]R
+*.[1-9][0-9][0-9]R
+*.eledsec[1-9]
+*.eledsec[1-9]R
+*.eledsec[1-9][0-9]
+*.eledsec[1-9][0-9]R
+*.eledsec[1-9][0-9][0-9]
+*.eledsec[1-9][0-9][0-9]R
+
+# glossaries
+*.acn
+*.acr
+*.glg
+*.glo
+*.gls
+*.glsdefs
+*.lzo
+*.lzs
+*.slg
+*.slo
+*.sls
+
+# uncomment this for glossaries-extra (will ignore makeindex's style files!)
+# *.ist
+
+# gnuplot
+*.gnuplot
+*.table
+
+# gnuplottex
+*-gnuplottex-*
+
+# gregoriotex
+*.gaux
+*.glog
+*.gtex
+
+# htlatex
+*.4ct
+*.4tc
+*.idv
+*.lg
+*.trc
+*.xref
+
+# hyperref
+*.brf
+
+# knitr
+*-concordance.tex
+# TODO Uncomment the next line if you use knitr and want to ignore its generated tikz files
+# *.tikz
+*-tikzDictionary
+
+# listings
+*.lol
+
+# luatexja-ruby
+*.ltjruby
+
+# makeidx
+*.idx
+*.ilg
+*.ind
+
+# minitoc
+*.maf
+*.mlf
+*.mlt
+*.mtc[0-9]*
+*.slf[0-9]*
+*.slt[0-9]*
+*.stc[0-9]*
+
+# minted
+_minted*
+*.pyg
+
+# morewrites
+*.mw
+
+# newpax
+*.newpax
+
+# nomencl
+*.nlg
+*.nlo
+*.nls
+
+# pax
+*.pax
+
+# pdfpcnotes
+*.pdfpc
+
+# sagetex
+*.sagetex.sage
+*.sagetex.py
+*.sagetex.scmd
+
+# scrwfile
+*.wrt
+
+# svg
+svg-inkscape/
+
+# sympy
+*.sout
+*.sympy
+sympy-plots-for-*.tex/
+
+# pdfcomment
+*.upa
+*.upb
+
+# pythontex
+*.pytxcode
+pythontex-files-*/
+
+# tcolorbox
+*.listing
+
+# thmtools
+*.loe
+
+# TikZ & PGF
+*.dpth
+*.md5
+*.auxlock
+
+# titletoc
+*.ptc
+
+# todonotes
+*.tdo
+
+# vhistory
+*.hst
+*.ver
+
+# easy-todo
+*.lod
+
+# xcolor
+*.xcp
+
+# xmpincl
+*.xmpi
+
+# xindy
+*.xdy
+
+# xypic precompiled matrices and outlines
+*.xyc
+*.xyd
+
+# endfloat
+*.ttt
+*.fff
+
+# Latexian
+TSWLatexianTemp*
+
+## Editors:
+# WinEdt
+*.bak
+*.sav
+
+# Texpad
+.texpadtmp
+
+# LyX
+*.lyx~
+
+# Kile
+*.backup
+
+# gummi
+.*.swp
+
+# KBibTeX
+*~[0-9]*
+
+# TeXnicCenter
+*.tps
+
+# auto folder when using emacs and auctex
+./auto/*
+*.el
+
+# expex forward references with \gathertags
+*-tags.tex
+
+# standalone packages
+*.sta
+
+# Makeindex log files
+*.lpz
+
+# xwatermark package
+*.xwm
+
+# REVTeX puts footnotes in the bibliography by default, unless the nofootinbib
+# option is specified. Footnotes are the stored in a file with suffix Notes.bib.
+# Uncomment the next line to have this generated file ignored.
+#*Notes.bib
+
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+\documentclass[11pt,a4paper]{scrartcl}
+\usepackage{algorithm}
+\usepackage{algpseudocode}
+\usepackage[utf8]{inputenc}
+\usepackage[margin=2.25cm]{geometry}
+\usepackage{hyperref}
+\usepackage{listings}
+\usepackage{xcolor}
+\usepackage{lmodern}
+\usepackage{booktabs}
+\usepackage{multirow}
+\usepackage{graphicx}
+\usepackage{float}
+\usepackage{multicol}
+\usepackage{tikz}
+\usepackage{listings}
+\usepackage{pgfplots}
+\pgfplotsset{compat=1.18}
+\usepackage{subcaption}
+\setlength{\parindent}{0cm}
+\setlength{\parskip}{0.3em}
+\hypersetup{pdfborder={0 0 0}}
+%\usepackage[nomessages]{fp} no easter eggs this time
+\usepackage{amsmath}
+\DeclareMathOperator*{\argmax}{arg\,max}
+\DeclareMathOperator*{\argmin}{arg\,min}
+\usepackage{minted}
+
+\definecolor{codegreen}{rgb}{0,0.6,0}
+\definecolor{codegray}{rgb}{0.5,0.5,0.5}
+\definecolor{codepurple}{rgb}{0.58,0,0.82}
+\definecolor{backcolour}{rgb}{0.95,0.95,0.92}
+
+\lstdefinestyle{mystyle}{
+  backgroundcolor=\color{backcolour},   
+  commentstyle=\color{codegreen},
+  keywordstyle=\color{magenta},
+  keywordstyle=[2]{\color{olive}},
+  numberstyle=\tiny\color{codegray},
+  stringstyle=\color{codepurple},
+  basicstyle=\ttfamily\footnotesize,
+  breakatwhitespace=false,         
+  breaklines=true,                 
+  captionpos=b,  
+  keepspaces=true,                 
+  numbers=left,  
+  numbersep=5pt,
+  showspaces=false,                
+  showstringspaces=false,
+  showtabs=false,
+  tabsize=2,
+  aboveskip=0.8em,
+  belowcaptionskip=0.8em
+}
+\lstset{style=mystyle}
+
+\geometry{left=2cm,right=2cm,top=2cm,bottom=3cm}
+\title{
+\vspace{-5ex} 
+Assignment 3 -- Software Analysis \\\vspace{0.5cm}
+\Large Extended Java Typechecking
+\vspace{-1ex} 
+}
+\author{Claudio Maggioni}
+\date{\vspace{-3ex}}
+
+\begin{document}
+\maketitle
+
+\section{Project selection}
+The assignment description requires to find a project with more than 1000 lines
+of code making significant use of arrays or strings. 
+
+Given these requirements, I decide to analyze the Apache Commons Text project
+in the GitHub repository
+\href{https://github.com/apache/commons-text}{\textbf{apache/commons-text}}.
+
+\subsection{The Apache Commons Lang Project}
+The Apache Commons family of libraries is an Apache Software
+Foundation\footnote{\url{https://apache.org/}} sponsored collection of Java
+libraries designed to complement the standard libraries of Java. The Apache
+Commons Text project focuses on text manipulation, encoding and decoding of 
+\textit{String}s and \textit{CharSequence}-implementing classes in general.
+
+All the source and test classes are contained within in the package
+\textit{org.apache.commons.text} or in a sub-package of that package. For the
+sake of brevity, this prefix is omitted from now on when mentioning file paths
+and classes in the project.
+
+I choose to analyze the project at the \textit{git} commit
+\texttt{78fac0f157f74feb804140613e4ffec449070990} as it is the latest commit on
+the \textit{master} branch at the time of writing.
+
+To verify that the project satisfies the 1000 lines of code requirement, I run
+the \textit{cloc} tool. Results are shown in table \ref{tab:cloc}. Given the
+project has more than 29,000 lines of Java code, this requirement is satisfied.
+
+\begin{table}[H]
+  \centering
+  \begin{tabular}{lrrrr}
+    \toprule
+    Language & Files & Blank & Comment & Code \\
+    \midrule
+    Java & 194 & 5642 & 18704 & 26589 \\ 
+    XML & 16 & 205 & 425 & 1370 \\ 
+    Text & 6 & 194 & 0 & 667 \\ 
+    Maven & 1 & 23 & 24 & 536 \\ 
+    YAML & 6 & 39 & 110 & 160 \\ 
+    Markdown & 4 & 40 & 106 & 109 \\ 
+    Velocity Template Language & 1 & 21 & 31 & 87 \\ 
+    CSV & 1 & 0 & 0 & 5 \\ 
+    Properties & 2 & 2 & 28 & 5 \\ 
+    Bourne Shell & 1 & 0 & 2 & 2 \\ 
+    \midrule
+    Total & 232 & 6166 & 19430 & 29530 \\
+    \bottomrule
+  \end{tabular}
+  \caption{Output of the \textit{cloc} tool for the Apache Commons Text project
+    at tag \textit{78fac0f1} (before refactoring is carried out).}
+  \label{tab:cloc}
+\end{table}
+
+\section{Running the CheckerFramework Type Checker}
+
+The relevant source code to analyze has been copied to the directory
+\textit{sources} in the assignment repository
+
+\begin{center}
+\href{https://gitlab.com/usi-si-teaching/msde/2022-2023/software-analysis/maggioni/assignment-3}{\textit{usi-si-teaching/msde/2022-2023/software-analysis/maggioni/assignment-3}}
+\end{center}
+
+on \textit{gitlab.com}. The Maven build specification for the project has been
+modified to run the CheckerFramework extended type checker (version 3.33.0) as
+an annotation processor to be ran on top of the Java compiler. Both source code
+and test code is checked with the tool for violations, which are reported with
+compilation warnings. To run the type checker simply run:
+
+\begin{verbatim}
+mvn clean compile
+\end{verbatim}
+
+in a suitable environment (i.e. with JDK 1.8 or greater and Maven installed). To
+additionally run the Apache Commons Text test suite and enable \texttt{assert}
+assertions (later useful for CheckerFramework \texttt{@AssumeAssertion(index)}
+assertions) simply run:
+
+\begin{verbatim}
+env MAVEN_OPTS="-ea" mvn clean test
+\end{verbatim}
+
+The state of the assignment repository when the type checker was first ran
+successfully is pinned by the \textit{git} tag \textit{before-refactor}. A copy
+of the CheckerFramework relevant portion of the compilation output at that tag
+is stored in the file \textit{before-refactor.txt}.
+
+No CheckerFramework checkers other than the index checker is used in this 
+analysis as the code in the project mainly manipulates strings and arrays and a
+significant number of warnings are generated even by using this checker only.. 
+
+\section{Refactoring}
+
+\begin{table}[!ht]
+    \centering
+    \begin{tabular}{lrr}
+    \toprule
+        Warning type & Before refactoring & After refactoring \\ \midrule
+        argument & 254 & 241 \\ 
+        array.access.unsafe.high & 130 & 117 \\ 
+        array.access.unsafe.high.constant & 31 & 28 \\ 
+        array.access.unsafe.high.range & 22 & 22 \\ 
+        array.access.unsafe.low & 59 & 58 \\ 
+        array.length.negative & 3 & 3 \\ 
+        cast.unsafe & 2 & 2 \\ 
+        override.return & 12 & 12 \\ \midrule
+        Total & 513 & 483 \\ \bottomrule
+    \end{tabular}
+    \caption{Number of CheckerFramework Type Checker warnings by category before
+    and after refactoring.}
+    \label{tab:check}
+\end{table}
+
+Table \ref{tab:check} provides a summary on the extent of the refactoring
+performed in response to index checker warnings across the Apache Commons Text
+project. In total, 513 warnings are found before refactoring, with 30 of them
+later being extinguished by introducing annotations and assertions in the code
+in the following classes:
+
+\begin{multicols}{2}
+\begin{itemize}
+\item AlphabetConverter
+\item StringSubstitutor
+\item similarity.LongestCommonSubsequence
+\item translate.AggregateTranslator
+\item translate.CharSequenceTranslator
+\end{itemize}
+\vfill\null
+\columnbreak
+\begin{itemize}
+\item translate.CodePointTranslator
+\item translate.CsvTranslators
+\item translate.JavaUnicodeEscaper
+\item translate.SinglePassTranslator
+\item translate.UnicodeEscaper
+\end{itemize}
+\end{multicols}
+
+
+
+
+\begin{listing}[H]
+\begin{minted}[linenos,firstnumber=139]{java}
+public static int toMillisInt(final Duration duration) {
+    Objects.requireNonNull(duration, "duration");
+    // intValue() does not do a narrowing conversion here
+    return LONG_TO_INT_RANGE.fit(Long.valueOf(duration.toMillis())).intValue();
+}
+\end{minted}
+    \caption{Method \textit{toMillisInt(Duration)} of class
+    \textit{time.DurationUtils} in Apache Commons Lang 3.12.0.}
+\end{listing}
+
+\section{Conclusions}
+
+{\color{red}
+Did using the checker help you find any bugs or other questionable design and implementation choices?
+
+> no bugs found, couple of design choices
+
+How complex was it to apply the checker, and what benefits did you gain in return?
+
+> not so complex, lots of false positives
+
+Compare the checker’s trade-off between complexity of usage and analysis power to that of other software analysis techniques you’re familiar with (in particular, those used in previous assignments).
+}
+\end{document}
+