In Our Time (BBC R4) did a recent episode called &quot;P vs NP&quot; [1] which talked about graph isomorphism, and might serve as an introduction to this.<p>There&#x27;s an MP3 download at the link. I don&#x27;t think it&#x27;s UK only.<p>[1]: <a href="http:&#x2F;&#x2F;www.bbc.co.uk&#x2F;programmes&#x2F;b06mtms8" rel="nofollow">http:&#x2F;&#x2F;www.bbc.co.uk&#x2F;programmes&#x2F;b06mtms8</a>