Map overlay & algebra
=====================

.. raw:: html

    <iframe src="https://docs.google.com/presentation/d/e/2PACX-1vRzplynA06IpCm3gjrkTYD8OznEwlt8zILmQ7uuc7gZyW-aI2qUQWYud2qy1sPZF_MQ1ApFY9mAI__P/embed?start=false&loop=false&delayms=3000" frameborder="0" width="960" height="569" allowfullscreen="true" mozallowfullscreen="true" webkitallowfullscreen="true"></iframe>