#8203;</em> (three-dot) Symmetric Difference Notation</dt>
<dd>
<p>A similar notation <em>r1...r2</em> is called symmetric difference
of <em>r1</em> and <em>r2</em> and is defined as
<em>r1 r2 --not $(git merge-base --all r1 r2)</em>.
It is the set of commits that are reachable from either one of
<em>r1</em> (left side) or <em>r2</em> (right side) but not from both.</p>
</dd>
</dl>
</div>
<div class="paragraph">
<p>In these two shorthand notations, you can omit one end and let it default to HEAD.
For exampl