umber: "AMS"
      }
    },
    tex2jax: {
      inlineMath: [ ['$','$'] ],
      displayMath: [ ['$$','$$'] ],
      processEscapes: true,
    },
    "HTML-CSS": { 
      preferredFont: "TeX", 
      availableFonts: ["STIX","TeX"], 
      styles: {".MathJax": {}} 
    }
  });
</script>

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS-MML_HTMLorMML">
</script>

<h1 id="19-knowledge-in-learning">19. Knowledge in Learning</h1>

<div class="car