anchor.diff:  <p>
   Each problem domain may have one or more <em>variants</em>, which concern
   different manners of implementation or random instance generation.  E.g., the
  -traffic of Dubins cars domain (cf. Section 7) has a simulation variant, which
  +traffic of Dubins cars domain has a simulation variant, which
   relies on Gazebo, and a physical variant, which involves a real testbed of
   several Kobuki bases as well as an overhead pose tracking system.
   </p>
  
positive.code: title: definitions and rules
  use_mathjax: true
  ---
  
  <div id="banner">under construction!</div>
  
  <h2>Problem domain descriptions and competition rules</h2>
  <p>
  
negative.code: </p>
  
  <p>
  There are three <em>problem domains</em>.  Within a problem domain, a problem
  <em>instance</em> is a particular workspace, arrangement of obstacles, labeling
  of the workspace, selection of parameters for the robot dynamics, and a task
  formula.
  