using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(\$[^\n$]*[^\s$])(-|=|\+)([^\s$][^\n$]*\$)";
string input = @"\end{theorem}
A $k$-periodic sequence has the property that $s_i = s_{i + k}$ for all $i = 0,1,\dots$.
Thus a $k$-periodic sequence $(s_i)_{i = 0}^\infty$ may be represented by any finite sequence $(s_i)_{i=a}^{a+k - 1}$, where $a$ is usually chosen to be $0$.
Sadly our Fibonacci sequence examples are not defined over a finite field but over the naturals and thus are not necessarily periodic.
Examples such as these may be interpreted to have a period of $\infty$.
The period and related stability of linear recurrence sequences in regard to linear complexity has a very rich and broadly studied background~\cite{DingZiaoShan1991}.
\begin{theorem}
\label{th: max period is m-sequence}
\cite[Theorem~6.33]{LidlNiederreiter1994}
A linear recurrence sequence $s$ over a finite field $\gf_2$ with linear complexity $n$ has a maximum possible period of $2^n-1$.
\end{theorem}
\begin{definition}
\label{de: m-sequence}
A sequence which has maximum period for giv";
foreach (Match m in Regex.Matches(input, pattern))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx