% https://tex.stackexchange.com/q/13635/ \documentclass{article} \usepackage{xsim} \DeclareExerciseEnvironmentTemplate{theorem:remark} { \par\addvspace{\baselineskip} \noindent \textit{% \IfInsideSolutionF{\XSIMmixedcase{\GetExerciseName}~}% \GetExerciseProperty{counter}}% \GetExercisePropertyT{subtitle}{ \textup{(#1)}}% . % } {\par\addvspace{\baselineskip}} \DeclareExerciseHeadingTemplate{exercises}{\subsection*{Exercises}} \xsimsetup{ exercise/template = theorem:remark , exercise/within = section , exercise/the-counter = \thesection.\arabic{exercise} , print-collection/headings = true , print-collection/headings-template = exercises } \DeclareExerciseCollection{prime numbers} \DeclareExerciseCollection{Zeta function} \xsimsetup{collect} \begin{document} \collectexercises{prime numbers} \section{Prime Numbers} A \emph{prime number} is a positive integer other than $1$ that is only divisible by $1$ and itself. \begin{exercise}[subtitle=Euclid's Theorem] \label{ex:euclid} Show that there are infinitely many prime numbers. \end{exercise} As you will show in Exercise \ref{ex:euclid}, there are infinitely many primes. The number of primes that are smaller than a given natural number $n$ is denoted $\pi(n)$. \begin{exercise} Find an asymptotic formula for $\pi(n)$. \emph{Hint:} You might find Exercise \ref{ex:zeta} helpful. \end{exercise} \collectexercisesstop{prime numbers} \printcollection{prime numbers} \collectexercises{Zeta function} \section{Zeta function} The zeta function is given by $\zeta(s) = \sum_{n=1}^\infty n^{-s}$, where $s$ is a complex number with real part bigger than $1$. \begin{exercise}\label{ex:zeta} Extend $\zeta$ as far as possible and find all zeros of the function. \end{exercise} For example $\zeta(2) = \frac{\pi^2}{6}$. \collectexercisesstop{Zeta function} \printcollection{Zeta function} \end{document}