Regex for a sentence boundary : <p>I am trying to write down a regex expression for sentence extraction in a piece of text. In my definition, sentence starts with capital letter <code>[A-Z]</code> and ends with <code>.|!|?</code>. However, that is not all. Before the sentence start there should be a dot '.', question mark '?', exclamation mark '!', white space or beginning of string. Also, after the end of sentence, there should be white space (or not) followed by capital letters or end of string. </p>

<p>These rules are here to exclude the following false sentences</p>

<blockquote>
<pre><code>Maria has cat etc. my dog. (one sentence not two!)
https://i-am-cat-and-dog/Explain-what-you-are-doing. (not a sentence)
Cats Dogs Cars (not a sentence)
</code></pre>
</blockquote>
